Originally Posted by Xel
I think youre confusing yourself. Return to Castle Wolfenstein was released in 2001 and had a SP component developed by grey matter(Now Treyarch, developer of CoD3/5), and a Multiplayer component developed by Nerve Software.
The multiplayer was a giant hit, so much so that they released a version for the xbox in 2003. It ended up being the most played game on XBL for quite some time, and got very positive reviews for its MP component. A version for the ps2 came out also, but only had single player because psn wasnt really that big back then.
Then in 2003, splash damage(Guys who worked on enemy territory: quake wars and are now working on brink with bethesda games) worked on a expansion pack for PC to RTCW, they named it Return To Castle Wolfenstein: Enemy Territory. This was meant to be a full retail release, but they could never finish the SP so it released for free as a MP only title.
RTCW AND RTCW:ET Both had multiplayer.
OK I stand corrected as I checked the MANUAL for RTCW I see there is MP there. Did play some on the PC but could never really get into the game because no one ever worked together as a team.