how does it all work?
those of you who are/have developed a game using steam, how do you test things while the game is being developed without an app id?
is there a way of getting an app id without a finished game?
you’ll receive your AppID if you are allowed to sell your game on Steam. So after passing Greenlight or a custom deal with Valve or a publisher, you’ll get the AppID. Before that you can’t work with the Steam SDK.
Are you sure that is the case? Most game developers would not want to wait ~6 months before having a game that is greenlit to test it with many of the Steam features.
I do not want to publish the game on steam (and therefore will not have my own AppID), but would like to be able to integrate with some steam functionality (overlay, friends, maybe match list).
Am I allowed to use AppID 480 for that?
Are there any published rules about AppID 480?
No they don’t. If what you’re saying were true, no one would develop for Steam… Valve created a test project called SpaceWars with appID: 480 for anyone to test their games with Steam’s API and Subsystems… Just know that with multiplayer functionality, many developers use this appID and you will need to adjust your MaxPublicConnections variables to a high number to avoid issues finding their sessions.