After the basic rules there are level-specific sections in which I clarify any potential matters of contention, give special rulings to get the best combat and maintain the spirit intended, and give helpful reminders (mostly about enemies you might otherwise overlook, or about consequences of the basic rules). For each level the remarks are listed in order of progression through the level.

Basic rules

Here are my four basic rules (including some of the rationale behind them) plus the timing conventions.

Reality rule: Continuous play with no reversion

No dying or reverting to a checkpoint, or getting bounced back for any other reason (e.g. Keyes dying in level 3). In short, no reversion. Or to put it another way, no artificial time-rewinding nonsense. If you die, that's it - run failed. Think of it like you're playing 'for real'. Every mistake counts. Also, no pausing the game (including to save and resume). Play should be continuous. This all adds to the realism and tension, and the physical challenge.

Kill rule: Trigger and kill all enemies, with exceptions

Apart from various exceptions to keep the gameplay enjoyable and fair, all available enemies must get triggered and killed, including Sentinels, so you'll need to take a sufficiently inclusive route for that. It's ok to bypass enemies as long as they're dealt with at some point, but there are cases where the game might remove or kill enemies after a while, and such artificial assistance is forbidden.

If a normally accessible enemy somehow becomes an unfair target, hard to get at, you can skip him. There are some enemies which are routinely hard to get at which you're allowed to skip (think of them as just 'hazards'), but I cover those in the level-specific details.

There are three special rules for Flood:

(1) You can skip spores. They're too incidental and it would often be hard to tell if they're all dead.

(2) Once a combat Flood is down you can count him 'killed' as long as he remains out of sight. But if you subsequently see him upright again and he's well in range of one of your weapons other than a rocket launcher or sniper rifle, he's back on the menu again. You're often going to have to take these guys down a second time anyway just for self-protection, but in places where Flood are relatively sparse, this 'once-down' rule potentially lets you blast your way through non-stop without having to keep waiting around to check for reanimation, something that wouldn't play well.

(3) You can skip carrier Flood that spawn anywhere back along the way you came. Such spawning is often quite a way back and quiet too, so it's not easy to be aware of, and it often doesn't feel like a threat worth dealing with.

Exceptions aside, let me emphasize that in a situation where enemies spawn repeatedly, you're obliged to kill them all even if it takes quite a while for the spawning to stop. You mustn't do anything to lessen the amount you're due, like running so far past that the game considers the area finished with. Only move on from the skirmish area when it's clear that nothing more is coming. In most places where repeated spawning occurs, you have the option of backing out of the relevant trigger area to pause further spawning for a while. That's allowed, though it'll obviously slow you up.

There are some places where covies or combat Flood spawn behind you, perhaps putting you in a nasty sandwich. They must be dealt with of course; don't pretend you didn't know they were there!

Note: In regard to being sure all enemies have been dealt with in a given area, usually you'll be well aware of the situation if you're experienced, and the game often gives you some help too (e.g. rooms go quiet, music fades, Cortana speaks). But on occasion it may be appropriate to take a quick look. If making a video, keep in mind that you want it to be clear that you handled things fully, so your run isn't thrown into doubt.

Tricks rule: No tricks

No 'tricks' or suchlike, including the exploitation of glitches to sneak an advantage; weapon glitches in particular. The whole spirit of this is to do good honest soldiering which respects the combat dynamics Bungie intended, and which aims for comparative realism. In particular:

  • No fast reloading tricks ('backpack reload' or whatever). They remove an integral part of proper realistic combat, namely the skill of judging when best to do a time-consuming reload.
  • No overheat prevention tricks to minimize the problem of plasma weapon overheating. They rob the gameplay of an element of skill - that of rationing fire to avoid an overheat.
  • No 'double melee' tricks for doing two melee attacks extra fast.
  • No repeated swapping of weapons as you move, to keep more than two handy. Whether you think of it as a trick or not, it subverts Bungie's two-weapons-only ethic and goes against realism.
  • No grenade jumps or rocket jumps. We're keeping things more down to earth here and don't want folk to have to master fancy jumping techniques to be able to compete. The focus here is on combat skill.

Jumping up onto things without explosive assistance is allowed even if it enables you to take a novel tactical approach Bungie maybe didn't anticipate. We'll consider that to be ingenuity rather than trickery. Likewise any falling is allowed. You're also allowed to aim with a sniper rifle then switch to a rocket launcher for precision rocket aiming. It's somewhat artificial but there are other types of aim assistance too and I decided it was best to just allow them all.

If you're not sure whether something is allowed or not, ask me and I'll give a ruling if needed.

Allies rule: No friendly kills by deliberate attack, normally

Causing the death of an ally by deliberate attack is forbidden, unless you're being blocked in such a way that you can neither jump over nor go around him. This is for the sake of realism and atmosphere, and especially to prevent the cheap use of Marines as handy sources of frag grenades when needed. When attacking enemies however, collateral allied deaths are fine. By all means take a "Move it or lose it!" attitude when allies are in harm's way.

Timing conventions and cutscenes

Unless otherwise specified, times go from when you have full control and vision - e.g. the moment you exit a Pelican or in some cases skip a cutscene - to when you've boarded a Pelican or lost full control and vision as things start fading out to a final cutscene. However, there's a special convention for the start of level 1 and details also for the starts of levels 7 to 10. Be sure to follow those to the letter or your run will be invalid, just the same as if you clearly violate any other rule. Round your time up to the nearest second.

You can skip any cutscene designed to be skippable (via button press) in the Xbox version, but that's all. You mustn't use trickery to skip a cutscene or avoid it triggering, or to trigger it early. Also, all expected non-skippable cutscenes must play. If for some odd reason one doesn't, the run is invalid. That's to prevent anyone getting a big advantage from a lucky quirk which had nothing to do with combat skill.

Level 1: The Pillar of Autumn

Start convention: On Heroic and Legendary there's a white fade-out of the opening cutscene. Leave the controls completely alone until you see "Find Captain Keyes on the Bridge", and consider that your starting time. On Normal or Easy, likewise start your time from that message, but you can be standing wherever you like (there's a tediously unskippable calibration sequence prior to this, though at least there's a checkpoint near the end, which you could save so you can avoid most of that sequence on successive run attempts).

You can skip the enemies you encounter before getting armed of course. Can't do much about those!

After the cutscene on the bridge, don't leave the bridge so fast that you fail to get a loaded pistol and meet some Grunts - a glitch in the game. A safe way of ensuring you get them is to pause for a checkpoint before leaving the bridge (as seen in BCM22), but it's also viable to leave slightly before that if you care to try and judge it right.

Reminder: As you near the final airlock area, make sure you get any Grunts lurking quietly down a side-corridor.

Note: The final cutscene won't trigger until the Grunts past the airlock are dead. Therefore, if you do get the cutscene you'll know that those Grunts got killed. That's handy as it can save you going up there to check.

Level 2: Halo

Reminder: The starting time is the moment you're able to advance, as you don't have full control until then.

Both of the first two Banshee pilots must be killed, even though the last remaining will try to fly off.

Reminder: The light-bridge cutscene must play. This cutscene can fail to play if there's fighting going on, so you may want to make sure there isn't any.

In the second part of the level you can tackle the three survivor areas in any order, and you can skip guards at entrances you don't actually use (it wouldn't play well having to make long trips just to get them). Banshees get triggered after you deal with a first area and must be dealt with before entering the next.

In the cliffside survivor area, driving up onto the hill which overlooks the structure is classed as a trick, hence disallowed.

Level 3: The Truth and Reconciliation

Let Cortana finish saying "Stick to the higher ground to the right" before you enter the first area, otherwise you won't get the covies which are meant to spawn on the path just beyond (1 Elite, 2 Jackals, 6 Grunts).

In the dustbowl area you must wait to deal with a dropship. You can expect it to be triggered when the enemy count has dropped below five, as long as you haven't triggered a passage checkpoint yet. As for the two possible enclosure Grunts, you're not obliged to make them spawn, but if they do spawn they must be killed.

As you may know, it's possible to get extra Marines in the grav-lift battle. I'm not sure whether Bungie intended that, but we won't class it as a trick as it happens quite naturally. It's allowed.

On arrival at the hangar, covies intermittently fire on you from above but they're not the fairest of targets, sometimes retreating out of sight. You can skip any of these guys if you want. Any you don't kill will be gone by the time you reach their location.

Level 4: The Silent Cartographer

You must finish the landing battle before tackling any other area.

You must cause the main facility's door to lock, shutting you out. I know the game lets you visit the two facilities in either order, but this standard order gives you more enemies. There's no need to kill the gold Elite before the door locks (he'd only rejuvenate anyway); leave him for later.

Note: When you think you've killed the cloaked Elites in the security substation, you don't have to count the bodies (5 on Legendary). If things have gone quiet and nobody steps out to shoot at you when they would've, that'll do. The same goes for the cloaked Elites at the end of the level (6 on Legendary).

Reminder: After using the security substation, some Jackals get dropped in the Hunter area you passed through earlier (you hear the dropship humming). They must be killed at some point.

Level 5: Assault on the Control Room

Reminder: Just past the crashed Pelican area, enemies other than Ghost pilots should spawn on the left and right (an Elite and two minors in each case, on Legendary). If the game fails to spawn them all, which seems to happen if you reach the trigger point prior to wiping out the initial cluster near the Marines, the run is invalid as we want all enemies. So, you'd better wipe out that cluster before advancing too far.

All Banshee stealing is considered a trick, hence disallowed. Banshees can't be used.

You can skip the third Wraith as it's often out of sight on its ledge, hence not a reliably fair target.

Reminder: At the cavern, Grunts are sometimes in distant dark places, though they wake and head for Shades when required. Be sure they all die. Legendary gives 2 groups of 3 on the left and a group of 2 on the right.

You can skip the tower Banshee unless it finds you and attacks, in which case it must be dealt with.

After the tower there are normally some Hunters and Elites who spawn in the pass. In certain circumstances (such as when a manned enemy Ghost remains) the Elites can fail to spawn. That's allowed (because I realized it was problematic to disallow).

Reminder: In the area beneath the twin bridges, don't forget to deal with the Elites in the trough passages.

After going up in a lift, you reach a room which includes an Elite in a raised housing. He'll usually come down if you advance far enough, but if he stays put even after you've gone through the central part of the room and even after you've sent two grenades or rockets inside, you can skip him.

Reminder: Also in that room, an Elite spawns later, sometimes behind you rather than with the minor enemies in the exit passage, so don't forget him. Until the music fades, not all covies here are dead.

Reminder: After going down in the final lift, be sure to kill all cloaked Elites (2 on Legendary).

In the final outdoor area you can get onto the spine of the structure if you like. We won't class it as a trick, since it's easily reachable. But bear in mind that at some point you'll still need to enter the second and third tunnels, otherwise the group of Hunters and Grunts on the upper level won't spawn.

Level 6: 343 Guilty Spark

On the way to the facility you can skip any Flood. They're only fleetingly glimpsed, hence unfair targets.

Reminder: In the maze-like facility, enemies are often scattered around on a different level to you, so you may need to look around a bit. They all have to be killed of course.

Once you leave the facility, you can skip Flood, who maybe spawn indefinitely anyway. Just get to the tower.

Level 7: The Library

Start convention: If you choose to let the opening cutscene play (perhaps to include some of it to make the start of a movie look nicer), leave the controls completely alone until the orange transportation effect ends, and consider that your starting time.

Reminder: Exceptions aside, you're obliged to accept all the spawning on offer. There's a lot of it in this level. It may be worth having a slow trial run to start with, to make sure you know where it all is and how long it can last for - especially if you're used to just dashing through the level. Otherwise you might end up missing out some enemies.

Reminder: Don't forget all the carriers lurking in corners and whatnot; keep your eyes peeled as you go.

Shortly after exiting the first lift, the Monitor says "Flood activity has caused a failure in a drone control subsystem. I must reset the backup unit. Please, continue on." You must continue to the area of the door (medkit nearby) and not retreat out of this situation, else you won't get your proper dose of hectic Flood spawning. Fight it out fair and square.

After the fourth door there are two routes you can take to the next. The standard route goes left where a group lurks in a wide open area, and those guys must die regardless. If you instead go straight ahead from the fourth door and clamber over two prongs of the 'circle' to approach the next door from a novel angle, some Flood intercept you and must be killed; but if you don't go that way, those guys can be skipped.

As you near the fifth door, there are one or more Flood in a very obscure place over a far prong of the circle. They can be distantly visible when you use the alternate route just mentioned, but they won't have been visible at all via the standard route. Whichever route you take, you can skip these obscure Flood.

Towards the end of the third floor there's a nasty situation where you're trapped between two doors and Flood emerge from two outlets. It's actually possible to hide safely until the far door opens, but that's not allowed. You can do your best to hide when your shield needs recharging, but otherwise you must allow the Flood to remain aware of you, so you'll have to fight for your life.

Reminder: As you approach the third lift, carrier Flood start to spawn slowly from high outlets. Naturally you should pop any you see on approach, but after that you can potentially head on to the lift, invoking the rule about ignoring carriers that spawn behind you.

Level 8: Two Betrayals

Start convention: If you choose to let the opening cutscene play (perhaps to include some of it to make the start of a movie look nicer), leave the controls completely alone until the white suddenly ends, and consider that your starting time.

You must kill all foot soldiers before you nab the first Banshee. This is to encourage the most interesting and serious combat, rather than rewarding the high-risk tactic of rushing straight for the Banshee, something that relies more on luck and multiple attempts rather than actual combat skill.

Squeezing a Ghost through the gap in the broken door leading to the cavern is a trick, hence disallowed.

In the final battle all foot soldiers must be killed before you nab a Banshee, except that you can normally skip the cloaked Elites as they're not always easily located. If you notice one firing on you though, he must die.

Level 9: Keyes

Start convention: If you choose to let the opening cutscene play (perhaps to include some of it to make the start of a movie look nicer), leave the controls completely alone until the white fade-out completes, and start your time from when you then begin moving.

Shortly after the start, you reach a gaping hole. You can skip the enemies on the other side, but you can only jump down when Cortana has finished saying "Chief, we need to jump now!". That'll give you a good bit of combat to get warmed up.

In the second outdoor skirmish area, Flood continue to spawn for a while (jumping into a deep pool with awkwardly high rim), but only at a frustratingly slow trickle that doesn't feel worth hanging around for. So here's the rule for this area. You can leave once you reach a stage at which there's nothing alive on dry ground, other than spores.

In the area past the sniper rifle, Flood only stop spawning after you reach the fight area. So do that and deal with things (including any Flood up on the arch), then you can be on your way.

Near the entrance to the grav-lift area, pause if necessary until Cortana says "Power source detected", else the game may fail to spawn covies and Flood, which is not allowed. You don't have to kill all enemies here (things are somewhat messy and sometimes covies get hidden in the gloop), but you can only use the grav-lift once you're able to look back down the slope from near the top and see no enemies other than spores for at least two seconds. You also mustn't be taking fire from the side; any such aggressor must be killed.

Shortly after reboarding the ship, you find yourself overlooking a room with a Wraith in it. You're not allowed to jump down; you must take the passage, where Flood lurk. Part way there, Flood repeatedly drop from the ceiling. You're obliged to see out the attack of course.

Reminder: In the Wraith room, don't forget to trigger the Flood behind the massive door (where the overshield is). They seem to get triggered once the initial Flood have been wiped out, as long as you're in the room.

Reminder: Some while after dropping through the small hole past the Wraith room, there's another place where Flood repeatedly drop from the ceiling, and other Flood spawn back the way you came. Don't forget about the latter guys, who tend to stand around quietly.

When you reach the hangar with the four Elites on the central platform, don't use the door on the left yet; that's for later. You're ultimately heading for the far door. But on the way, you trigger the first of around 32 covies and Flood, who continue to spawn as existing combatants die. Make sure you hang around for the full works; all must die. Tech note: spawning gets temporarily suspended if you stray out of a certain 'trigger area' (see Keyes hangar battle for details). Don't mistake that for being the end of spawning. If you want to be sure you've had all possible spawning, stand anywhere in the trigger area (e.g. on or near the platform). If no new red dots show up on your tracker within a few seconds, the spawning is over.

Reminder: On the way to the control room some enemies arrive in a dropship below, but you can leave them for later if you want; they'll still be around.

Reminder: After escaping from the control room (with all Flood and covies killed of course), there will be enemies to trigger in the passage going down from the third level, and also in the passage going down from the second level.

Reminder: At the end there are lots of covies on the ground floor of the hangar, and potentially in the passage that goes around at the back (troops from the first dropship). All must die.

Level 10: The Maw

Start convention: If you choose to let the opening cutscene play (perhaps to include some of it to make the start of a movie look nicer), leave the controls completely alone until the white fade-out completes, and start your time from when you then begin moving.

Shortly after passing through the cryo-bay, you go through an access way and emerge into a corridor. To the right are some covies near floor arrows indicating Engineering and the Armory. To the left are some Sentinels. It's actually possible to trigger repeated Flood spawning to the left, but it's an unsatisfactory stop-start affair and it's the wrong way too (you might not even know about it), so you can skip those Flood.

Reminder: After going through the cryo-bay and then a long hard-fought corridor, there's an access way coming up. But as you near it, Flood start to spawn in the small compartment nearby, where the well-hidden overshield was (you'll hear them). All must die. Wipe out a wave, get the next one, and so on. Note: a new wave only gets triggered when you're in the access hatch area.

Once you reach Engineering or the Armory, you can skip enemies for the rest of the level, as things get messy and kind of urgent! Besides which, Flood spawn in Engineering forever. Also you don't have to wait at the scripted area for Echo 419; you can just keep going.

Nonstandard runs

In some levels there may be scope for some interesting nonstandard play by allowing certain tricks after all, contrary to the standard blanket "no tricks" ruling. In addition, I'm aware that some people might be used to playing with certain tricks, and I don't want them to feel completely excluded (though I personally wouldn't like to watch combat involving weapon tricks, as they just seem too cheap to me). So what I'll say is this. If you want to do a 'nonstandard' run in which you're allowing certain trickery, then ok fine, I'll potentially still be interested in hearing about such runs and adding links to them. But if you're posting a video make sure you clearly indicate what you're allowing, in departing from the standard rules.

Banshee stealing

An allowance I've got in mind for level 5 is as follows. "Banshee stealing allowed" means that you can steal and use Banshees, though if you steal the platform Banshee, you're no longer allowed to skip the high Wraith as it's going to be a fair target, and you must also kill the stranded Banshee pilot as he'll likewise be fair game. Also, if you have a Banshee in the tower area, the pilot for the tower Banshee must be killed, as he'll be a fair target (whether he's in his Banshee or not).

This allowance could make for an enjoyable nonstandard experience (still combat-based of course), but bear in mind that as you advance, you'll need to be quite low down in places to trigger enemies (and yes you do still have to trigger and kill them of course).