Checkpoint delaying

Posted March 30th 2007, updated later


As you'll know, there are certain events that trigger checkpoints in a level. Maybe you entered a certain area, maybe you killed the last of some enemies - that sort of thing. When I talk about 'triggering' a checkpoint, I just mean that you're now due the checkpoint. The game owes it you, so to speak. Normally you'd get it within a few seconds of it being triggered, but certain things can cause a checkpoint to be delayed - potentially until you want it - and that's what I want to talk about here.

Uses of checkpoint delaying

Checkpoint delaying can be extremely useful, as it allows you to get a checkpoint at a more convenient time or place than normal. In particular, suppose you have to do a tricky task that might require many attempts before you manage it acceptably well. The thing to do there if possible, is to trigger a checkpoint somewhere and keep it delayed until you're in position ready to attempt the operation. This way, each time you fail and revert for another go, you're immediately ready for the next attempt. Very efficient, and you're likely to achieve success all the more quickly.

Another use is when getting the final checkpoint for a save you're creating. That's going to be the start checkpoint of your save, i.e. the place you'll be starting from each time you play the save (I refer to it as the 'battle start checkpoint' in the case of a battle save). You can potentially delay it until you're happy with how things are. For example, in creating a twin bridges megabattle, you can use a Banshee to trigger a checkpoint and keep it delayed until you've led the enemy to a particular starting area, in order to influence their eventual attack (perhaps to cause a more intense attack, or to make them attack from a particular direction). When you're satisfied with the enemy layout, you can finally get the checkpoint. That makes your battle optimally replayable for such an enemy layout. Each time you revert to fight again, the enemy are already in position; you won't need to spend time getting them into position all over again.

As another example of getting a final checkpoint, suppose you've set up some explosive fun involving a Warthog and a pile of grenades (yeah, you know what I'm talking about). You can delay your checkpoint until you're in position ready to set off the explosion. Each time you revert, you won't have to first spend a while reaching the scene; you'll be right there and it'll take only a moment to make things go bang. Ideal for launching the hog again and again.

Delay by enemy threat

As I eventually realized after a lot of playing, the game likes to delay checkpoints while it considers you under threat from the enemy. That makes good sense of course, because a player might be quite annoyed to get a checkpoint in the middle of a sticky situation. Revert, get killed, revert, get killed… there might be no escape! Even if the situation wasn't as severe as that, you wouldn't want to be in a position where you could get taken by surprise before getting your bearings after reverting. That would be poor game design.

If an enemy has you in their sights and you're within range, or even quite a way out of range, that's likely to qualify as a threat as far as the game is concerned. In normal play you're unlikely to experience such delays, as checkpoint triggers are generally designed to occur when you're unlikely to be under threat. If you're doing something the game wasn't really expecting though - and we do quite a bit of that here at Bad Cyborg - it becomes more common. Deliberately remaining under threat is one way of causing a checkpoint delay.

Delay by weapon use

Delay by enemy threat was actually the only method I knew about until March 2007, when a thoughtful contact alerted me to an old HBO forum post by xbill (March 3rd 2003), describing how to delay a checkpoint by continuously firing the plasma cannons of a Banshee or Ghost. The post also made passing reference to the method of throwing a grenade (which xbill credited to FrogBlast), or jumping. I couldn't find much other material so I did some experimenting of my own to try to get a fuller picture. In regard to weaponry, here's my conclusion, which I've given a name.

Active ordnance principle: While you're sufficiently near, the game likes to delay checkpoints while there's any type of fired or thrown ordnance still active, i.e. in the air or waiting to go off. In short, while there's any 'active ordnance'.

It doesn't matter who does the firing or throwing. Could be yourself, could be covies, Marines or whatever. Active ordnance is active ordnance.

As to the reason for this principle, here's my best guess. Maybe Bungie figured that if there's active ordnance around even though the game hasn't judged you as being under threat, then (a) it could nevertheless be disconcerting to revert to such a situation, and (b) maybe the threat-judgement algorithm was giving a poor judgement anyway; maybe you really are under threat (e.g. maybe a stray bullet could reach you by a freak ricochet or two). So, maybe the delay policy stems from a user-experience concern, just like with enemy threat if my thoughts about that were right.

One special point: plasma grenades fizzing away on a frozen Elite (or other NPC) seem to delay checkpoints regardless of how far away you get. Even across loading points!

Using the principle

To use the active ordnance principal as a method of delay, you'll want to know approximately where or when the checkpoint is going to get triggered, so you can start firing or throwing in advance.

In regard to weaponry with automatic fire ability such as Banshee's plasma cannons or the needler, note that you don't have to keep the trigger down and fire continuously. You can just fire individual shots, as long as you make sure there's always at least one shot in the air. You can help yourself there by trying to aim where your fire will have a long way it can travel, so you don't need to fire so often to maintain the delay. With the Banshee's plasma cannons I prefer to just fire individual shots when possible, so the controller isn't shaking around so much and so things are less noisy. If you're manoeuvring in a confined space though, you'd want to keep the trigger down. With a needler, individual shots will use up your clip slower of course. When you need to reload, you can potentially continue the delay by jumping a few times.

Actually, with the Banshee I often use intermittent shots from the fuel rod gun rather than the plasma cannons. That way you don't need to fire so often; and also I find it more engaging.

In case you're wondering, yes you can even delay by using bullets from the pistol or AR, or the Warthog's chain-gun, or the Scorpion's machine gun. I tested to make sure. The only difference from using plasma or needles is that the various projectiles become inactive much quicker, due to the much higher shot speeds. Such weapons are less practical for delaying checkpoints but they still fall under the same principle. Same with the shotgun, but the high shot speed coupled with the relatively short range and slow rate of fire makes it unreliable. Even keeping the trigger down to fire as fast as possible, the game sometimes ended the delay I was trying to maintain, before I got to the last of my loaded shells. The one bit of weaponry I found too awkward to get a conclusive result on was the Scorpion's cannon; but I'd be surprised if that was any exception.

Taking care near surfaces

In his post xbill warned that you should try to avoid bumping or scraping against things when firing in the Banshee or Ghost, as this can sometimes cause the delay to end. Here's what I think is going on there. If you bump into something, the plasma fire can get momentarily diverted into a very close surface (wall or floor or whatever), hence each plasma pip hits very quickly. Potentially so quickly that for a fraction of a second the air is empty of plasma in between shots, even if you're firing continuously. At that point the game is freed up to give you the checkpoint (though whether it immediately takes that chance is another matter, which may lend things a degree of unpredictability). So, it's not the bump itself that's causing the delay to end; it's just that your plasma didn't have far enough to fly, for your current rate of fire. You could potentially get a premature checkpoint just by being sufficiently near a surface you're aiming at; no bumping needed.

Acknowledgements, and a movie

Thanks a lot to the Halo contact who alerted me to xbill's old forum post. Thanks also to Ducain who subsequently referred me to an HIH forum thread about a movie by 3rd Person, which contains some checkpoint delay methods in action in level 5, a movie Louis Wu enthused about in the HBO news.

Delay by jumping

The game also likes to delay checkpoints while you're jumping. This is extremely useful when you want to delay a checkpoint on foot (though it doesn't seem to work in The Library). Unlike with weapon use, which gradually eats up your ammo, you can do it indefinitely. You also don't have to concern yourself with aiming a weapon in a direction where the shot will have a decent distance to travel (to make sure there's always a shot in the air). Plus it's a whole lot quieter, if that's any concern. If for some reason you are using weapon fire to delay things, jumping can be used to continue the delay when reloading.

Tips on technique

When you land from a jump, how long is it ok to wait until you jump again? Fortunately the game seems to give you a bit of leeway here, which is plenty enough to keep moving your thumb to the joystick to steer your course. I did a bit of testing. Running along, it seemed ok to jump as late as the third step after landing (you can hear the footsteps). After landing, I was doing step-step-jump, hitting the jump button at the time you would've heard the third step. Whether that's always ok, I'm not sure. It may be cutting things a little fine, because it definitely wasn't ok to jump as late as the fourth step. There may be some unpredictability in how long you've got, so I'd feel safer jumping on the second step, or very shortly after.

When you don't need to alter course (maybe you're not going anywhere at all), you can simply keep the jump button down if you like, which takes jumping into auto-repeat mode.

Why does it happen?

As to why the game likes to delay checkpoints when you're jumping, my best guess would be that it's simply to prevent a situation where you revert and find yourself in mid-jump, something which could be momentarily disorienting. Just a user-experience concern then, same as with the other two delay policies if my thoughts about those were right. Bungie were possibly also thinking that "A jump is quickly over, so our delay policy won't hold up the checkpoint long". And they probably weren't expecting anyone to be jumping repeatedly. I mean, why the heck would anyone do that eh?

Switching delay methods

You're entirely free to switch delay methods part way through some delaying. As long as you're always using some method, the delay should continue. For example, if you're flying along using Banshee fire to maintain the delay, you can land and continue the delay with jumping, or whatever.

Banshee landing and take-off

If you want to continue a delay after landing in a Banshee, it's a good idea to make sure that your final bit of Banshee fire has a good distance it can travel, to give you enough time to dismount and start delaying things on foot. I recommend using the fuel rod gun for that, as the shot travels slower than plasma pips. Get close to the ground, send off a shot in a direction where it'll have far to travel (as best you can manage), quickly land, and get jumping to continue the delay.

When delaying on foot and you want to continue via Banshee, it's pretty safe to make the switch by boarding immediately after a jump and then immediately firing a fuel rod blast or getting the cannons going. As long as you don't leave much time between those two things, the game won't get much opportunity to give you the checkpoint. If you want to be completely safe however, throw a grenade before boarding. The same boarding advice goes for a Ghost.

Note: If you want to continue a delay when changing Banshees, you can either use the above two methods consecutively, or do things in one go by firing a blast then making the change quick.


With all three causes of checkpoint delay, I've been careful only to say that the game likes to delay checkpoints. I mean to imply that in some cases it may not. In fact, some checkpoints seem undelayable - presumably because there's some special overriding reason for prompt issue - while others seem delayable for only a few seconds before the game cancels them entirely.

Undelayable checkpoints

For example consider the start checkpoint of level 5, due shortly after you get off the Pelican. If you throw a grenade quick, you can get the checkpoint while the grenade is still active. Likewise, continuous AR fire or pistol fire will fail to delay the checkpoint, and so will jumping. Note also that the game surely considers you under enemy threat here; in which case that hasn't managed to cause a delay either. Nope, ain't nothin' gonna stop this checkpoint, apparently. The start checkpoint of level 4 is just the same. It's not hard to guess at the rationale here. What if the checkpoint was delayed and you got killed before getting it? You haven't actually had a checkpoint to be sent back to!

Are there any undelayable checkpoints that aren't start checkpoints? I'll be on the lookout. And if you find any examples, I'll be happy to hear from you. Stop press: I've noticed that there are checkpoints in level 7 that you can't delay by jumping.

Briefly delayable checkpoints

In some levels there are repeatable checkpoints, i.e. which you can get again and again - as many times as you like. In the tricks community I've seen them called 'infinite checkpoints' or 'infini-points', but I prefer to just use the term 'repeatable'. In level 2 they include the two entrance checkpoints for each of the three final survivor areas, while in level 4 they include five around the periphery of the island. However, the ones in levels 2 and 4 are only briefly delayable, as mentioned to me by BigGruntyThirst. They can be delayed for a few seconds (you'll be ok with 4 jumps if auto-jumping), but after that the game cancels them. Level 4 also has some repeatable checkpoints associated with the entrances into the two facilities, but those are likewise only briefly delayable.

Checkpoints which are only briefly delayable are typically less use than normal ones as you can't get them far from where they're triggered, but the checkpoint cancellation aspect might actually be useful in some situations, namely if you want to avoid getting the checkpoint.

Jumping in The Library

In much or all of The Library (I haven't tested it all), jumping does not delay checkpoints. However, enemy threat and weapon use seem to work as usual. A good way of keeping a checkpoint delayed indefinitely is to have an armless combat flood following you about. Kill him when you want the checkpoint. Spores will cause a delay by enemy threat too but they need to be pretty close. Within several metres or something like that.

Tunnel checkpoint in level 5

Undoubtedly the most useful checkpoint for delay purposes is the 'tunnel checkpoint' (as I call it) in level 5, Assault on the Control Room. It was actually mentioned in that post of xbill's I spoke of earlier, so I guess he found it pretty darned useful too. It's triggered in the section of paved tunnel that leads from the snowy two-Wraith area to the cavern. Specifically, there are five humps in that section, and the trigger zone is the area stretching from the peak of hump 2 to the peak of hump 4, including the flat peaks themselves. In practice this means that you trigger a checkpoint on the second hump you reach, whichever way you're heading through the level. Typically you'd be in a Banshee, in which case you'll be able to delay the checkpoint with plasma fire. But you could instead be in a Ghost, again using firing to delay, or on foot and jumping to delay.


Very usefully, the tunnel checkpoint is repeatable; you can get it as many times as you like. The only limitation is that there's a time delay imposed between successive triggers, which on PAL Xbox is about 73 seconds (the timing may be slightly different for NTSC and PC). If you were to merely wait in the zone, you could actually get checkpoint after checkpoint; you don't have to leave then return.

Weapon disappearance oddity

Let me just mention a weapon-related oddity concerning this area. When you're playing through the level and enter the checkpoint zone (i.e. reach the second hump peak) after leaving the two-Wraith area, any rocket launcher you're not carrying seems to vanish, even if it was picked up at some point, and even if you're looking at it. Very quirky. I've seen other weapons vanish too. I've never managed to get both of the launchers past that point to use in later fun, but it's possible to get both of the early sniper rifles past.

Fully delayable checkpoints in level 4

As already mentioned, level 4 has quite a few checkpoints which are only briefly delayable, after which they get cancelled. But if you want a checkpoint you can delay arbitrarily (with jumping or whatever) so you can get it at a particular spot, there are still plenty of options. In particular, there are many triggered by wiping out certain enemy groups around the island (groups you can potentially leave unfinished until you're ready to start your delaying). For example the group of Jackals just around the corner from the landing zone, the group of Grunts and Elites just a bit further along, the group near the overturned Warthog outside the entrance into the interior of the island, the group up the subsequent narrow passage, the Hunter pair beyond, the Hunter pair in the security substation, and the group comprising Hunters and Jackals patrolling in a chamber in the main facility.

Carrying them through other checkpoints

I haven't done exhaustive testing but I suspect that any fully delayable checkpoint can be carried through briefly delayable ones if required. By this I mean that you can pass though the trigger zone for a briefly delayable checkpoint without your ongoing delayed checkpoint getting cancelled. This usefully widens the scope for where you finally get the checkpoint.