I used to do Gmod RP, but most of it's really low-quality. You know, DarkRP - but I preferred 1942 RP as well. I started with RP on Starcraft: Brood War... UMS maps like Feyvern RP mostly.
You can still find Neverwinter Nights RP servers, but that can be a bit of a nuisance because support for the game has been cancelled. You have to use alternative services to actually find servers.