iEntertainment Network announces the release of WarBirds 2103, the continuation of this long-running series of combat flight simulations. The new version is offered on this page, and it includes a 30 day subscription to the MMOG version of the game as well as a single-player game. They also announce plans to follow this early next year with a free version of the game to be supported by microtransactions. Here's word on the new content in the new version as well as OS X Lion support:

For Apple Macintosh players, a brand new Mountain Lion OS version, with advanced graphics is now available. Thirteen new aircraft have been added to WarBirds 2013 including the two ground attack aircraft, the Hawker Sydney Typhoon and the Ilyushin IL-2 Shturmovik. Other new simulation aircraft include a new Lancaster bomber, the tank busting Hurricane IID, and Mitchell B-25D- “Strafer” low level attack aircraft.

New features added include updated damage models on over 50 aircraft, new weapons loadouts adjusted to more exact historical options, and new fragmentation, incendiary, and tank busting weapons. IENT expects to release a FREE MicroTransaction version of WarBirds 2013 early in 2013. Players get basic aircraft and can win or purchase upgrades with microtransactions.