Alien Swarm Holdout Mode

posted in: Projects | 9

A big part of the Alien Swarm mod I’m working on is spawning aliens so that they attack in massive waves, rather than in response to triggers set off by the player. Luckily for me, the game’s SDK already includes a lot of this functionality in its incomplete Holdout mode (operated by the “asw_holdout_mode” entity).

This tutorial details setting up a Holdout map, but it notes that instances of “asw_holdout_spawner” need to be named after wave names, which isn’t the case. Essentially, a Holdout map requires at least one “asw_holdout_mode”, one “asw_spawn_group” and one “asw_holdout_spawner” entity.

“asw_holdout_mode” activates the mode itself and requires a reference to a Holdout file (as shown below). Examples of these (such as “holdoutwaves_default.txt”) can be found in “C:\Program Files (x86)\Steam\steamapps\common\alien swarm\swarm\resource\holdout\”.

Holdout Mode Entity

The Holdout files themselves define one or more waves, which break down into one or more entries. Each Entry defines things like: type of alien, number of aliens, delay between spawning, and which SpawnGroup should be used to control spawning.

"WAVE"
{
	"Name"						"Intro"
	"EnvironmentModifiers"		"0"
	"Resupply"					"1"
	"ENTRY"
	{
		"AlienClass"		"asw_drone"
		"Quantity"			"5"
		"SpawnDelay"		"0.0"
		"SpawnDuration"		"0.0"
		"SpawnGroup"		"Spawn_Left_Group"
		"Modifiers"			"0"
	}
}

SpawnGroup refers to an “asw_spawn_group” entity which can be placed in Hammer. A SpawnGroup is an entity that groups up to eight Spawners (“asw_holdout_spawner” entities) together. Any aliens defined in a Wave Entry will then be divided evenly among each specified Spawner.

Alien Swarm SpawnGroup

“asw_holdout_spawner” defines where aliens will actually spawn, unlike “asw_spawn_group”. Judging by its source code it doesn’t do anything different to the regular “asw_spawner”, but I suppose it may well do when Valve come to officially completing and releasing the Holdout mode.

A Wave ends once every spawned alien has been killed at which point a Resupply overlay appears and a timer begins counting down to the next wave (if any). Click here to download the VPK map file shown below and in the video above. It features the necessary entities to make use of “holdoutwaves_default.txt”.

Alien Swarm Holdout Map Test

9 Responses

  1. romilly hills
    | Reply

    i was pretty surprised survival mode wasn’t in the released game, but i guess they left it up to the community. cool you got it working and personally i think you should polish up a nice survival mod + map before you move onto your rts hybrid.

    incidentally is that video the reason you were hoping in and out of asw t’other day :p

  2. Karn Bianco
    | Reply

    I reckon Holdout/Survival will be officially released in an update at some point. The underlying code doesn’t seem to be quite finished yet.

    I’ve been thinking about putting together a nice Holdout map to see how things play out. Could be useful in helping us decide on structures to include.

    This video is just a small part of what I’ve been tinkering with personally, hopefully we’ll have some cool stuff to show off soon!

  3. romillyhills
    | Reply

    “I reckon Holdout/Survival will be officially released in an update at some point” – depends which conspiracy you subscribe to, because it does seem like it was bait for the community to switch to steamworks, hence the free-ness and mod tools, as opposed to an actual game they were going to properly release and support.

    on a more random note, did the alien killing in that video contribute to achievements? (also can you make achievements for your mod?)

  4. Karn Bianco
    | Reply

    I still think they’ll release some updates of their own to keep the game active so that modders/mappers will want to continue working on it.

    No achievements, though, it says we’re cheating. Also we can’t add our own achievements without the Steamworks SDK, as far as I know.

  5. rawrm-illy hills
    | Reply

    on a more random note, this new blue is… odd… can’t… tell… why… just odd.

    on a less random note, comments on the maternity post don’t work… bug or feature?

    • Karn Bianco
      | Reply

      I haven’t decided if the new blue (based on the hyperlinks, etc.) works better than the old one (I’ve switched back for comparison)

      No comments on portfolio posts is probably a “feature”. This isn’t my theme, so I haven’t tested everything yet!

  6. romilly 'zebra' hills
    | Reply

    fair play, also i didn’t *actually* notice your website exists now, always just tapped in ze blog address.

    it might just be my 2am eyes, but this blue is nicer, and if it turns out to be the same then ignore me.

    anyway *like* the fact you have website actual now, add more!

  7. Precious
    | Reply

    It’s much easier to unaedstrnd when you put it that way!

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