Named Game of the Year by over 50 publications, Valve's début title blends action and adventure with award-winning technology to create a frighteningly realistic world where players must think to survive. Also includes an exciting multiplayer mode that allows you to play against friends and enemies around the world.
(This Deathmatch map is ONLY for Half-life 0.52) Custom Deathmatch map for Half-Life Alpha (V1.2 Map by nebrine)
v1.2 Update released.
Gameplay Video: Youtube.com
Can't say that I understand the point in making a multiplayer map specifically for the alpha version of the game, but some of the details look nice in the video.