I have an idea of how this could be achieved, in fact...
Much in the same way as user profile field's are added, something similar could be adopted on a multi-level format:
Admin Side
Game management
Level 1 : Game Addition/Managing/Deletion
Level 2 : Game-specific "profile fields" for attributes concerning each game: i.e. Spell Casting Level for magic related games, Number of Kills for fighting related games etc
User management
An additional file could be added to the Admin CP to control these on a per-user basis, based on those who have filled out profiles - This could be added to an ACP XML nav file...
User Side
Control Panel
Level 1 : Via User CP the user goes to their "RPG Profile" from the side-menu and are presented with the game(s) that the admin has added, and can select which game profile to alter at that time
Level 2 : Inside their game-specific RPG profile they can fill out the fields that they wish to that relate to the game
Main User Profie
User's can view specific rpg profiles that the user plays, as each game they created a profile for is added to a list, similar to "Public Usergroups" (optional game icons can be added)
Posting
Links to specific games users play in their posts (only if an icon for a game is available else it would clog up the interface)
Thoughts?
I could begin work within the next little while, and if you have any thoughts to add or whatever or have another way of doing it, ideas would be appreciated
Chris