it would be best to encourage expansion as long as it only goes in the direction of the original game, E.g.
1. No specific interest varients eg( cyberpunk,steampunk, ect)
2. only add things which would be considered in the same era as the game, (no AK-47s)
3. try to make the additions stay in the same general mood as the rest of the game, no ridiculous monsters, no damned crap such as that.
4. if any of the first three guidelines are broken don't bother uploading it.