Battles at the first tower

Posted November 14th 2007

Introduction

This article describes a suite of novel battles you can set up in the first barrier tower in level 7, The Covenant. By doing certain easy things you can quickly get 31 covies migrating to various areas and have some fantastic fun trying to stop them, or waiting for them to amass before attacking them. You can even have Marine support in some cases; for example you can arrange to have yourself and 4 Marines in the first room, standing in the path of a covie flood. Sound appealing? There's also lots of creative potential in that you can move containers around beforehand to block or hinder the covies, plus you can move those explosive blue plasma batteries ready to be set off at opportune moments! It's excellent stuff and I've been having a blast with it.

Covies on the move

The definite highlight here is the lobby migration battle. In that situation you'll be fighting enemies that are on the move and there are so many enjoyable ways of doing it. That's certainly what I've had the most fun with. The enemy dynamic there is sadly one you don't really get in normal encounters with covie foot-soldiers, where it's usually a case of attacking a group that holds a particular territory. Enemies coming your way in numbers is way more stimulating!

Preliminary advice

Here's some preliminary advice before I get to any specific battles.

Convenient base save

Start by getting a checkpoint outside and saving it to form a 'base save' you can then use to set up any of the battles I describe. For maximum convenience you'll want to be in a suitable state of preparedness though. Here's a checklist.

  • Be carrying your favoured weapon combo with as much ammo as possible, and be loaded with grenades.
  • Be carrying the cloaking device as it's handy in setting up battles.
  • Preferably don't leave the Shade or any enemy vehicle intact near the door, or an enemy may run out to man it later.
  • For now, don't have any Marines left alive or they'll get in the way of the set-up work I describe; let's keep things simple. Kill them if necessary. I'll cover Marine support later.
  • For extra convenience and flexibility, assemble a range of weapons near the door ready to choose from or to move indoors for a particular battle. Some of these may be weapons you deliberately gave Marines when back on the beach, effectively using Marines as couriers.

You'll get a checkpoint when you finish off the enemies outside, and this could potentially be used as your save point if you think you're prepared enough. Otherwise, take all the time you need to do any remaining preparation (such as forming that weapon stash I suggested), then drive off in the Mongoose to get a checkpoint back past the pool. Admittedly you're going to be further from the door each time you start your base save, but it'll only be a quick drive to get there.

When you set up a battle, usually you'll be able to get a later checkpoint that serves as a convenient battle start checkpoint to revert to for replaying. But unless you specifically save it, you won't lose your base save. When you've replayed your battle enough, you can get back to your outside checkpoint by exiting to the Xbox dashboard (hit the logo button then Y) then reloading and resuming; all ready to set up a new battle.

Battle rifle and Brute shot

My own favoured combo would be a battle rifle and Brute shot - a great combo for these battles. In regard to arranging a full battle rifle, note that you can use up your original one and get a fresh one from a Marine afterwards, which you can top up at the ammo drop later. If you left a few rounds in your original, you can potentially give that to a Marine before leaving the beach. In regard to getting a full Brute shot, check Prowler wreckage for topping up your ammo.

Nothing but teats and tedium

I strongly recommend that you have the IWHBYD skull on as you'll hear a lot of highly amusing chatter from the Grunts in these battles. And with 20 of the little blighters, that's a lot of chattering! I especially like the line about Flip-Yap. Or was it Yap-Flip? No, that was his brother…

The lay of the land

Here's a quick description of the indoor area where the battles will take place, just to familiarize you with a few terms I'll be using a lot. Initially you're in a small lobby with some transparent panelling at the end, then you get into the first room proper which is teeming with covies. Through the second door there will be more covies, some right away in a rather explosive ramp area, and some on the upper level where the lift is.

Reverting to replay

With all these battles you'll be due a checkpoint as soon as the last enemy dies (ignoring any enemies that went outside to man a vehicle - which can happen once they're in the lobby). But you can delay it by immediately jumping, to give yourself enough time to then use the Start button to revert. Actually it seems to me that if you jump long enough - 5 times seems sufficient - the checkpoint gets cancelled entirely; not that you need to go that far.

An alternative approach is to make sure you leave at least one enemy alive, so you can revert at leisure. It may grate a little not to wipe out the covies completely, but it's the safest way and frees you from having to be ready to do that jumping business. I often use this approach when tackling covies that are on the move, especially if I'm attacking them as they're coming though a door and I can't see how many remain on the other side. Maybe I'll let a Jackal speed past early on, and after that I can let myself go.

If you ever do get a battle end checkpoint, you can always get back to your saved checkpoint by exiting to the Xbox dashboard (hit the logo button then Y) then reloading and resuming.

Lobby migration battle

In this battle the covies will all be flooding to the lobby from the upper level and it'll be your task to stop them. Best fun in the building!

Setting up

The first part of the set-up work is to get all enemies collected on the upper level. Here are three options.

Option 1: Take the shortcut to the lift then jump back the way you came, to shelter for a moment. Enemies will retreat to the upper level but you haven't quite got them all yet. When the first room is clear, jump down and approach the second door to make 3 Grunts materialize on the other side. They'll head to the upper level too, but feel free to stick your head around the door to give them a shock so they'll hurry along.

Option 2: Trigger a retreat from the first room so you can then take an unpressured shortcut to the lift to make enemies retreat to the upper level. You can immediately bounce off down to cover.

Option 3: Simply run to the upper level then jump back down to the first room. This becomes less advisable on the higher difficulty levels of course, and there's a danger of losing enemies from friendly fire. Obviously cloaking will help.

Give everyone enough time to gather on the upper level, and do any battlefield preparations you want. Then activate the lift, preferably from below to avoid enemy fire - but you could use the shortcut to the lift if you like. Everyone heads for the lobby and the battle is now on. If you care to wait anywhere in the central area of the first room (or on the lift entry platform - but see later for special advice about that), you'll normally get a convenient battle start checkpoint just as enemies start to come through the door. Otherwise you'll have to make do with your original checkpoint.

Battle plans

There are all sorts of battle plans you can enjoy. Here are some ideas.

Get to the second door and try to stop them as they flood down the ramp from the upper level. If they manage to push forward in numbers you can always set off those plasma batteries. Hee hee!

Ambush them at close range at the second door where they have to file through. You could intermittently drop grenades in the doorway while backing off to reload or whatever. A shotty might be nice here, though you might have a job reloading fast enough.

Stand in the central area of the first room and see if you can fight them off without leaving. Maybe see how many enemies you can headshoot with a battle rifle as they come through the door.

Defend from just back through the entrance into the first room's central area. It has vertical transparent panels on either side. It's a great location providing plenty of cover. Occasionally you might be attacked by an enemy that came around a side-passage, but most will come through the central area.

Retreat back to the lobby and see if you can hold them off from there. Let 'em know it's a 'Cyborgs Only' zone. The transparent panelling will give you some good cover. You could block off one of the openings so you'll only have one side to worry about.

Get in their path but progressively fall back, trying to take them down one after another from a relatively safe distance.

Station yourself off to the side of their path somewhere and try to pick them off as they pass, like ducks in a shooting gallery. For example you could be down a side-passage of the first room, looking into the central area through an opening. Or maybe stand where you'll be able to shoot them in the back (or tag them on the back) as they pass unsuspecting.

After activating the lift, follow up behind the enemy and see if you can work your way through them as they migrate ahead of you.

So many delicious possibilities! See what else you can think up.

Blocking them off

In regard to battlefield preparations, you can of course block the enemy completely so they cluster somewhere. There are two ways of exploiting this.

One is simply to have fun attacking your captive mob. It's not really a proper migration battle but it's definitely good for letting off steam! One obvious example is to block the second door with a container. There's a big one handy just nearby. The whole mob will end up densely clustered behind it, and if you don't know how to have fun with a situation like that, you should hand in your cyborg licence immediately! Pile in the hurt with a Brute shot and grenades, or whatever. You can get behind the mob by jumping across from the lift base. And here's an idea. What if you've also taken the time to move all those plasma batteries down into that area beforehand? Ooh, that's gonna hurt. You can also block the third door by pushing a small container up the ramp (though the covies sometimes manage to push it aside).

The other thing you can do is blast your blockade to release the mob when you're ready, and then you've got a proper migration battle again. This 'temporary blockade' method can enable you to try fending off a flood in certain places; such as at the third door. I've had great fun releasing the mob there (after waiting for a handy battle start checkpoint in the first room's central area). Defending from near the ramp can be quite amusing because you can score headshots as enemy heads come into view (as they approach the door) before they can even get a shot at you. On Heroic I took down almost the whole lot like that with my battle rifle. Another fun place to defend from: standing on the ledge to your left as you come through the second door.

Platform shoot

It's possible to set up a version of this battle in which you're up on the lift entry platform. Enemies will start coming through the second door down below, and you're in for a whole heap of fun trying to stop them getting across the room. This 'platform shoot' is one of my favourite battle plans.

The simplest method of setting things up goes like this. After having made made all enemies collect on the upper level, activate the lift from below. Once the lift is gone, move up to the top of the lift base. After a short while, enemies start to come through the door and you'll normally get a checkpoint. Hop across to the platform and let the fun begin. In due course the lift will return and you can do 'rearguard shooting' from there if you want; i.e. shooting enemies that managed to clear the first half of the room. Don't you just love getting covies in the back?

A potential niggle with that simple method is that when you reach the platform, there will still be some enemies up on that level waiting to file out. If they spot you they're likely to attack for a while, making it hard for you to focus on the room below. You may even have to take cover, in which case some of the enemies below will be getting away. You can improve things a bit by delaying your fire for a few seconds to try to avoid getting noticed, and it helps even more if you can activate cloaking as you hop across. Sometimes there's no problem; you get a checkpoint and you find yourself pretty free to then open fire on the first enemies before they're more than a few metres into the room. Other times you get too much stick from nearby and it's frustrating.

So here's a refined method that remedies any such problem. After having made made all enemies collect on the upper level, move a container to block the second door, and maybe also move a plasma battery against it. Activate the lift from below. Hop across to the platform within a few seconds - preferably cloaked - then move into a nearby corner to hide until nearby enemies have gone. Move out onto the platform and you should get a checkpoint. Enemies are blocked at the door. Blast the container aside and you're off.

Note: If you use a small container on its side, you may see Grunts amusingly trying to hop up onto it but failing because there's not enough clearance. It's good fun to try to headshoot these hoppers in mid-air.

Late version

You can also set up a lobby migration battle that takes place after you've been up in the lift - perhaps to get your hands on a gravity hammer or invincibility device. Just block the second door with a large container before you take the lift, so enemies will get blocked (don't use a small one as they tend to push those aside in this case). When you come back down, blast it aside to let the enemies flood through towards the lobby. The battle is on! You'll actually have support from 2 Marines the game created for you (assuming you left none around). They try to stay near you, subject to remaining between the first door and the entrance to the first room's central area.

Some details regarding events in the control room. You can potentially kill the Brutes with the aid of nearby weaponry to avoid using up stuff you want to save for later. When the Brutes are dead you'll get a checkpoint. Gather any goodies you want, then deactivate the tower. You'll be due a checkpoint as soon as the cutscene is over (it's ok to skip the cutscene), and this will form your battle start checkpoint. But you can usefully delay it by jumping 3 or 4 times as you head for the lift immediately after the cutscene ends, so you get the checkpoint when close to the lift. That'll save you a small bit of running each time you revert to replay the battle. If you jump too long you won't get the checkpoint at all; but you can always revert to try again.

Lobby battle

In this battle you fight covies gathered in the lobby.

Setting up

Here are two methods of setting things up.

Method 1: If you want to be able to make any battlefield preparations - such as moving a few plasma batteries into the lobby to give the mob a nasty surprise later - start off as in the lobby migration battle to get all covies collected on the upper level, nicely out of the way (or at least make them leave the first room). After doing your preparations, activate the lift - ideally from below for safety - and let the enemies migrate. When it's clear, enter the central area of the room (or go out onto the lift entry platform) to get a convenient battle start checkpoint.

Method 2: Take the shortcut to the lift, activate it, and jump back to cover. Everyone heads for the lobby, but you haven't quite got them all yet. When the coast is clear (or even before it's clear) approach the second door to trigger 3 Grunts who'll join the exodus. If they don't see you they may stroll casually which is quite fun to watch, but if you want to speed them up, show yourself to give them a nasty shock. Once they're well on their way, enter the central area of the room (or go out onto the lift entry platform) to get a convenient battle start checkpoint.

Late version

As with the lobby migration battle, you can also set up a version of the battle that takes place after you've been up in the lift. Maybe you wanted to fetch a gravity hammer for example; that would make quite a mess in that jam-packed lobby!

Battle plans

Normally you'd attack the enemy from the way they came. But using cloaking - or maybe just running like hell - you can get past the lobby mob to tackle them from outside if you want. Moreover, if you've been up in the lift and you go to the ramp outside, you'll trigger the arrival of a Marine in a Warthog and he'll come to help out at the door, plus you should get a checkpoint. Meanwhile the 2 Marines the game created indoors for you will be trying to get through the lobby to join you. But unless you're playing on Easy I don't rate their chances too highly!

Upper level battle

In this battle you fight covies gathered on the upper level or on their way.

Setting up

Use a method from the lobby migration battle to get all covies moving to the upper level.

Battle plans

Once enemies are heading for the upper level, you can either let them collect before attacking (from either side), or you can immediately move to the upper level from the lift and try to fend them off as they arrive. Either way there are plenty of possibilities.

Marine support

Everything I've said so far has assumed you got rid of any Marines that came to the barrier tower with you. In this section I'll describe how you can get them to support you.

Slightly different base save

This time you'll want to start with a base save in which you brought the maximum 4 Marines along to the tower and carefully kept them healthy. There are lots of tactics you can use to minimize the amount of conflict they get exposed to, but I'll that to you to explore. All I'll say is that when it comes to the final enemies clustered around a Shade, perhaps the best approach is to blitz them with a Ghost, well ahead of the Marines so it's all over by the time they turn up. With thoughtful tactics I'd say it's possible to keep the Marines in near perfect health.

When you finish off the enemy, advance on foot down the path far enough to trigger the Marines into dismounting their vehicles so you can do any further preparations without them driving around annoying you. Don't worry, they won't go through the door until you do. Don't go in yet.

You can vary the later effectiveness of the Marines - and the atmosphere they produce -according to what weaponry you give them. Equip them as desired prior to getting your save checkpoint (you could always change it for a particular battle though). I'd advise against giving them a fuel rod gun as it's so powerful. That could give you a lot less to do in battle, plus it could be a safety concern for you.

As normal you'll finish your base save with either the checkpoint you get after finishing off the enemy (if you think you're prepared enough), or a later checkpoint obtained back past the pool. If you're going for the former, you'd want the Mongoose close at hand ready for blocking the Marines - or even already in position across the door.

Note: A base save with Marines can of course also be used for setting up solo battles if you kill the Marines before setting up a battle, or if the battle is going to be away from the lobby so the Marines will play no part.

Block the Marines before going in

Each time you set up a battle, leave the Marines blocked at the door so they won't be able to follow you inside yet. It's best to use the Mongoose for that. It's easy to drive into position across the door, and note that if you ever need to get over it while leaving it in position, you can do so crouched. Using a Warthog is clumsy and awkward, while a Ghost is inadvisable because a Grunt from inside may run to man it once alerted to your presence, releasing the Marines prematurely.

Marines in lobby migration battles

To get the Marines into a lobby migration battle, first get the enemy gathered on the upper level as normal and do any battlefield preparations you want. Release the Marines. They'll start heading for the second door. Before they get there, activate the lift (preferably from below). This not only triggers the enemy migration, it makes the Marines switch behaviour as the game expected you to be riding up. They'll now take up a holding position in the first half of the room. There are a few containers there plus a mast; you may like to have moved those out of the way to form a nice clearing. In due course the enemy start coming through the second door and you can get a battle start checkpoint as usual if you're in the central area or up on the lift entry platform. You don't have to fight alongside the Marines of course. Feel free to go off down a side-passage to form a crossfire for example. Lots of possibilities.

You can also get the Marines into a late version of the battle, i.e. taking place after you've been up in the lift. Set up a late version as normal except release the Marines before you ride up. On return, release the blocked enemies. The Marines will try to stay near you as best they can, subject to remaining between the first door and the entrance to the first room (except that when there are few enough enemies remaining, they may run out to man the Mongoose or something). It's a lot of fun to lend support from up on the lift looking down on them, and you've got good cover from covies up there. Another idea: draw them back into the lobby and defend from within.

Marines outside in lobby battles

I've already said how to get the Marines into a late lobby migration battle. If you've set things up for that but leave the building after releasing the covies, the Marines will follow and fight from outside the door when covies reach the lobby (actually they may board a Mongoose or something, but not if you blow it up first), giving you a lobby battle with Marine support. You also have the option of running to the ramp to trigger a checkpoint - which you can use as a convenient battle start checkpoint - and another Marine.

Marines in upper level battles

To get your Marines into an upper level battle, set up a battle as usual but release the Marines at an appropriate moment. They'll head through the second door to take up position near the plasma batteries. Er, not a good idea guys! You can join them there in an attack, or separately attack from behind the enemy.

Without blocking

I said to initially block the Marines at the first door, but it's possible to set up battles without doing that if you enter well ahead of them and use the shortcut to the lift to quickly trigger an enemy retreat so the room is practically empty by the time the Marines arrive. When they arrive you can draw them back to the lobby if needed as the last enemies withdraw. You can then finish off your battle's set-up work pretty much as normal.

Triggering a retreat from the first room

Some of my battle recipes involve triggering an enemy retreat from the first room. You can do it by dashing to the second door - just far enough that you'd be touching it if it was closed - then getting out of the way and back to cover. The enemies in the first room will head through immediately; some only as far as the ramp area, some to the upper level. You can perform the dash fairly safely using cloaking, but it's also possible to manage without if you want to save cloaking for later.

Your dash will also trigger all remaining enemies. Specifically, 3 Grunts materialize on the ramp behind the door as you near it, then other covies materialize further back when you get right to the threshold.

Favoured technique

Here's my favoured technique for doing things. Head down the right side-passage and activate cloaking just before you get seen by the Grunts, or maybe delay it an extra second or two. Hug the left wall and hop over the obstacles you meet. That helps keep you out of the way of enemies, plus it's fun. Skim the doorway then continue on around the first room to cover. Your cloaking will be fading but minor enemies tend to panic when they suddenly see you, so you're unlikely to take much fire if any.

The route is also viable without cloaking, even on Heroic. In this case I think it's definitely a good idea to hug the wall like I said, because the stuff you hurdle can partly block the lines of fire from enemies ahead or behind. On Heroic you'll probably end up with a bleeping shield but you can survive almost every time. Of course, there's also some danger that the enemy will damage themselves with friendly fire, especially if the Grunts get a bit grenade-happy. But if it doesn't work out to your satisfaction, you can always revert and try again.

Shortcut to the lift

There's a handy shortcut to the lift. In the left side-passage after the lobby, there are two stacked containers. Jump on top then diagonally across through an opening to reach the upper level. There are some goodies nearby: carbines, plasma grenades, and a power drain. The lift is an easy jump away. If you're taking the shortcut when the room is still teeming with enemies, you may want to use cloaking. It doesn't last long but it's enough to get you to the lift undetected if you're efficient.

The jump to the opening is quite tight and you should be crouched as you come over the opening, to get extra clearance. With practice you should be able to pull it off most of the time. However, you can make it easier by giving the top container a quick whack to nudge it closer, as long as you don't have the Cowbell skull on. E.g. whack the corner so the end angles around slightly.

Brief visit, to trigger a retreat to the upper level

Part of the interest in this shortcut is that it provides a way of triggering an enemy retreat to the upper level. Merely stepping foot on the lift is enough. You can jump on then bounce straight off to the right, or jump back the way you came.

Stepping on the lift is also enough to cause the materialization of additional enemies on or near the upper level, though not the 3 Grunts behind the second door. If you want all 31 enemies, you'll need to trigger those Grunts separately by approaching the second door.

Intended by Bungie?

I think this shortcut may have actually been intended as an option by Bungie, bearing in mind how inviting those unusually stacked containers are, and bearing in mind that the jump is just possible, thus requiring skill to pull off. There's also that cloaking device outside, which can last just long enough for you to reach the lift undetected - though it could equally be used to bypass enemies in other ways of course. Note also that the shortcut doesn't really break the game, because the bypassed enemies will still have a part to play, namely migrating to the lobby to give you a warm welcome when you come back down and try to leave. However, it can lead to a small potential glitch, namely allowing you to see 3 Grunts materialize before your very eyes if you near the second door from its rear side. But perhaps that was just an oversight.

Lift activation from below

Here's a little trick that comes in useful. It's possible to activate the lift (and thus trigger an enemy migration to the lobby) without actually being on it!

The pyramidal lift base has four wide fins; front, back, left and right as you approach. If you jump up onto a side fin and go up on its front edge then look up at a suitable angle, you can activate the lift. You'll get the onscreen prompt when you're looking in the rough direction of the lift switch - which you can't actually see because you're below the floor. If you prefer, you can move around to the front fin once you're at the top, to do it from there where you can actually see through to the switch. But I find that movement awkward.

Tip: Rather than looking around for the onscreen prompt and then hitting RB in response, it's easier if you're already keeping RB down. That way the lift activates 'automatically' as soon as the onscreen prompt appears.

Battlefield preparations

Prior to getting a battle under way, you have the option of making certain preparations in places from which the enemy has retreated. Here are the main options I'm talking about.

Moving containers

There are lots of containers around - supply cases in two sizes - and they can be moved to block off part or all of the enemy's route, potentially making them cluster behind a blockade, funnel through a small gap, divert a particular way, and suchlike. There's huge creative potential for making interesting situations like that. Containers can also be placed to give you cover or to serve as firing platforms. In other cases you may want to actually move them out of the way, to make a clearer battle area.

You can move containers with melee attacks, explosive blasts, or in the case of the smaller containers, by simply pushing with your body (they're a lot lighter). You can topple a container by hitting it at the top; the physics modelling seems excellent. Enemies rarely seem to have the wit to clamber over an obstacle you've placed, but they may barge smaller containers aside.

Moving plasma batteries

You can move those explosive blue plasma batteries into places where you can potentially set them off in battle to give the enemy a nasty surprise. There's one near the second door, and more through the door. They're very light and can be moved just by pushing with your body. When toppled over, they can be rapidly rolled along. There's some major mischief potential here, so don't miss it!

Arranging spare weapons

You can move spare weapons into handy positions ready for use in battle. In particular you could move some to near where you plan to get a battle start checkpoint, so that each time you revert to replay the battle you can quickly get armed with the combo you fancy. This will make your battle a lot more flexible.

Enemy numbers and behaviour

In total you get 2 Brutes, 9 Jackals (2 with carbines) and 20 Grunts, making 31 units of battle fodder. They're not all present right away though. Here's the detail.

When you enter the building the first room contains 1 Brute, 5 Jackals and 10 Grunts. There are also 3 Grunts on the upper level, potentially peering down at you. No other enemies exist yet.

When you near the second door or enemy numbers fall sufficiently, 3 reinforcement Grunts materialize on the ramp on the other side. Actually you can see that happen right in front of you if you approach from that side - something you can do after using the shortcut to the lift.

When you enter any of the area stretching between the threshold of the second door up to and including the lift (which could be the first bit of that area you touch, courtesy of the shortcut), you trigger 1 Brute, 4 jackals and 4 Grunts; some in the ramp area and some on the upper level.

Four enemy movement triggers

There seem to be four retreat or migration behaviours you can trigger, the latter three of which we've been exploiting to create our battles. Here's my understanding.

  • Retreat to the second door: Once you reach the final half of the first room's central area, the enemies in the first room retreat to near the door.
  • Retreat from the first room: Once you reach the second door, the enemies from the first room retreat through it; some only as far as the ramp area, some to the upper level.
  • Retreat to the upper level: Once you reach the third door or touch any of the adjoining surface through that door, including the lift floor (directly accessible via the shortcut of course), all enemies retreat to the upper level.
  • Migrate to the lobby: Once you activate the lift, all enemies head for the lobby (and music starts up), even if you don't ride up with the lift. Obviously Bungie intended you to get a warm welcome from any bypassed enemies before you get back outside!

I think I've covered all the best situations you can engineer by exploiting these triggers, but if you come up with any additional uses you think I'd want to know about, feel free to drop me a line.

Further remarks

Here a few assorted remarks.

Weeding out unwanted enemies

With all these battles, you can weed out any enemies you don't want. For example, maybe you don't want those carbine Jackals zipping shots into your armour? Or maybe you don't want any Jackals at all? Just pick off whoever you don't want before setting up your battle. A beam rifle can be useful for this; there were a couple outside in a container overlooking the Wraith. There are also a few carbines available.

Standing on containers

You can potentially shoot from on top of containers. However, Grunts and Marines seem to have no hesitation in hopping up to join you, which is a weakness of the AI that can be annoying. It's like the AI has failed to consider the possibility that the space might already be occupied by a seven foot cyborg. If anyone hops up, give 'em a firm whack I say!

Mongoose in battle

It's actually possible to get a Mongoose into the first room. You can't just drive it in; there's a bouncy forcefield effect that tries to keep it out. You have to push it through the door (with your body) and then keep pushing it until it's clear of the lobby - else it'll get pulled back to the door. Once past the lobby you can drive around, but the forcefield effect keeps you back from the lobby. You can potentially drive it around in a battle - perhaps do a bit of squashing. However, Marines will only man it after you've been up in the lift. Note also that a driver will be useless (er, I mean more useless than usual) as he won't actually drive anywhere.

Clambering Grunts

Grunts love clambering over containers, even when it would be much quicker to just go around them. They give little cries of exertion when doing so - you'll hear that a lot - and it's all quite cute and amusing. When the enemy retreats from the first room, the Grunts down the left side-passage tend to clamber over a container at the end and you can watch if you're in a good spot (maybe following up behind them).