X-Half-Life: Deathmatch (XDM) is an Unreal Tournament-style Half-Life 1 modification. XDM features Classic Deathmatch, Team deathmatch, Capture The Flag, Domination, Co-Operative, Last Man Stanging, Singleplayer game rules, new weapons, new high-quality maps, new hi-def models and lots of special effects. It is an Unreal/UT-style HL mod with tons of familiar stuff and atmosphere. 8) XDM continued where VALVe stopped. XHL provides extended features, effects and principles with FULL BACKWARD COMPATIBILITY. XHL pushes HL engine to its limits, don't underestimate the GoldSource! XDM - brings unreality to Half-Life since 2001!
I've played several mods that include new weapons, multiplayer gamemodes and singlplayer. The result is that so far this is the best mod i have played. (If this mod has just a few more things it might just get better than sven-co-op)