I had an idea to start a web based game, but have four instances running at once (ie w1.site.com - w4.site.com). You could have an account on each, and each would be separate (except for the forums). So w1 would have an identically laid out users table to w2 (each would have username, password, email etc), but different records.

I don't know the best and most efficient way to go about it though :D

Either having four separate databases, or having one, but with a column in each table representing the game (ie users.game_id). I'd also like to synchronise all items between them, but have separate mail, so I don't know the best way to make sure the items etc are the same, while keeping others different.

Does anybody have any experience doing something similar? I've only ever worked with one database at a time before. Thanks! :)