Limited support
This feature is only present in Portal 2: Community Edition. Source Mods
P2:CE and its menu system was designed as a gateway to sourcemods/standalone games. If a default campaign is specified (cvar: campaign_default), the game will use that campaign as the base menu state instead of the standard P2:CE menu. This can be helpful for mods that cannot or do not want to create a custom menu system (or simply as a starting platform while developing the mod).
Note:
There are extra considerations to take when developing a menu script that leverages the campaign system. Full details can be found on the Technical Notes page .