Defense of the Ancients 2 for Mac, free multiplayer battle game, released on Steam

Valve has announced the release of Defense of the Ancients 2 for Mac. DOTA2 is the standalone sequel to the hugely popular hugely popular DOTA, which first appeared as a mod for Blizzard's strategy game Warcraft III: Reign of Chaos. The Mac and Linux versions' release only lags the Window's release by about a week.

DOTA 2 is a real-time strategy game that combines elements of role playing games as well. You assume the control of one of two factions - the Radiant or The Dire - as you choose heroes to go into battle. Heroes - more than 100 of them - have special abilities and can level up as they gain experience.

Players must protect their own "Ancient," a base, as they send computer-controlled minions into battle. DOTA 2 is what's known as a MOBA, or Multiplayer Online Battle Arena. Each team can have up to five players.

There was some controversy when DOTA2 was announced because the original game was a mod, and some gamers thought the sequel should be free. In fact, the game is free to download and play - Valve makes money by selling items you can use in-game through a built-in store. It's similar to the system employed by another popular MOBA, League of Legends (or, for that matter, Valve's own popular team-based shooter Team Fortress 2).

System requirements call for OS X Lion or later, 4GB RAM, 8GB hard drive space and Nvdia 320M, Radeon 7000, or Intel HD 3000 graphics or better.