The Defense of the Ancients mod for Warcraft 3 has spawned no less than four retail titles now (Heroes of Newerth, Demigod, League of Legends, and Valve's upcoming Dota 2), and Las Vegas' Petroglyph Games is throwing its hat into the ring with another, called Rise of Immortals. Petroglyph, which has its roots in EA's Westwood Studios and is also working on an MMORTS for Trion, showed the game to me at GDC last week and, while it's safe to say that the growing "MOBA" (multiplayer online battle arena) genre is probably well covered already, they are planning to put a few new twists and turns on the still-developing formula.

The most central of these is more of an emphasis on PvE -- while League of Legends or Heroes of Newerth is centered around five players battling it out with five others online, Rise of Immortals plans to make playing versus the environment a viable goal, with levels that spawn monsters to fight and even award persistent items for you and your team. There are some other innovations, too, and Rise of Immortals seems like it will be an interesting experimental entry into this quickly evolving genre.