Half-Life Deathmatch: Source is a recreation of the first multiplayer game set in the Half-Life universe. Features all the classic weapons and most-played maps, now running on the Source engine.
TriNecatoR says
It's better than HLS, anyway we could build new maps with improved graphics for it, so it's not just a game, rather a platform on which mappers and modders can built own stuff (some like Alien Swarm or HL2DM).
Anyway, original HLDM I like much more.