Testing Portal 2 Co-Op Maps Alone
Template:Otherlang2 This is a guide on how you can test co-op maps alone utilizing the splitscreen capabilities of the Source engine. This also works for any existing coop maps. It does not require any modifications to the map file itself.
This does not cover the requirements for making a coop level in the first place.
Loading the Map
ss_map mapname
- Load
mapname
in splitscreen 2-player mode. Analogous tomap
in singleplayer. Likemap
, it is not required to add the trailing .bsp. ss_splitmode mode
- Changes the splitscreen mode.
ss_splitmode 0
: Use recommended settings based on widthss_splitmode 1
: Top-and-bottom splitss_splitmode 2
: Side-by-side split
If your map is stuck at the loading screen, try to shorten the vmf filename and recompile.
Dual Monitors
If you run dual monitors and want to split to each monitor, follow this guide
Controlling the second player
If you could actually play the coop map entirely as one player, it wouldn't be a very cooperative map. These are some ways you can control the second player.
in_forceuser
in_forceuser playerindex
- Take over the second player. All movement and other keybindings will be as if the second player used them. Requires cheats to be enabled.
sv_cheats 1
: Turn on cheatsin_forceuser 0
: Control player #1 (Atlas)in_forceuser 1
: Control player #2 (P-Body)
To make this easy to use, set a keybinding for it:
BindToggle "z" in_forceuser
- Swaps you between first and second player when you push "z".

Bind "z" "-moveleft; -moveright; -use; -forward; -back; -attack; -attack2; toggle in_forceuser"
.Use a controller
This is actually more complicated than it sounds unless you have two controllers available. Source will map actions of the first detected controller to the first player and there doesn't seem to be away to override this. The workaround is to either have two actual controllers or use trickery to make your computer think it has two controllers.
More information for this can be found on the Steam forums.
change_portalgun_linkage
This allows you to use the extra sets of linked portals without actually changing characters.
change_portalgun_linkage_id integer
- Changes portals fired to belong to the specified character or team.
change_portalgun_linkage_id 0
: Single-playerchange_portalgun_linkage_id 1
: Bluechange_portalgun_linkage_id 2
: Orangechange_portalgun_linkage_id [3-9]
: Extra / Reserved

Other useful console commands
cmd2 command
- Executes command as if typed by the second player.
cmd2 name Player2
: Sets the name of the second playerss_force_primary_fullscreen enable
- Makes the first player fullscreen if enable is 1, hiding the second player's view.
- There doesn't appear to be a way to do this with the second player, nor does holding Tab to show partner view (+remote_view) work.
External links
- Original version of this guide hosted at ThinkingWithPortals.com
- How-to: Split Screen Coop
- How-to: SplitScreen with 2 monitors
- How-to: Play Co_Op Alone