There's no denying that the World War II multiplayer shooter based on Valve's team Defeat day is one of their less popular games, but if you're burned in the recent doors of Team Fortress 2 and Counter-Strike Source, good news: Defeat Source Day is now available on Steam for Mac for only ten.
Needless to say, like all other Valve Mac ports, if you already own DoD for the PC, you do not have to pay again. Defeat day a good game but does not polish the other Valve games, particularly Team Fortress 2. If you want to play a similar game for free, I recommend Enemy territory.
With Defeat day Mac's official launch, the only major Source engine games that Valve has yet to release are the two that I most expected: Left 4 Dead and Left 4 Dead Ii. With Valve launching a new door every two or three weeks, I imagine we'll see both before the end of the summer.
As a final note, this is a good time to mention that we set up a new Cult of Mac group for Steam, so if you want to multiplayer with other Macheads, download Steam and join the cult.