[Mauzen]

You might like the Gothic 2 multiplayer mod. Philosophy behind it pretty much is the same as samp. A singleplayer game with an open world should get its multiplayer mode, including mapping and fully scriptable servers. Gothic has always been some kind of an insider game though.
Its another theme though, not a 90s drive-and-shoot game. Also its pretty difficult to get information about it if you cant speak polish, but theres also a international community.

https://www.youtube.com/watch?v=i08hjtCGdao