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.

The listed selling point behind the game, says lead designer Amanda Flock, is accessibility. "Being an RTS house, we're already made for a game like this," she says. "We don't want to reinvent the genre -- it is a MOBA at its core. But we want to make it more accessible than games like League of Legends and HoN." Accessibility, in this case, means an escape from the often less-than-kind human enemies, where groups of players face off against specially designed AI battles rather than a group of their own peers.

Petroglyph is also choosing to use persistent progression on the champion level, so instead of leveling up a "summoner" (in LoL terms), you'll be leveling up one of twelve champions available at launch. Leveling awards prestige points, which then get placed in three talent trees: offensive, defensive, and each champion's own personal tree. "The goal," Flock says, "is you max the champion tree, and then pick offense or defense to complement your playstyle."

Each of those trees opens up various customizations for the champions, and eventually you can unlock not only the standard abilities, but also a "signature." "And a signature," says Flock, "is like an ult on steriods. So an ultimate is 'Wow, that's a really powerful ability,' this is even more powerful than that. And it's called the signature because it sort of encompasses your character's core role, and emphasizes it with a great deal of power. At about siege level 25, you should have enough points in your skill tree to unlock that."

Items are also persistent per champions, and some items will only drop from PvE levels (though they'll probably also be available through microtransactions -- not all of the details on drops have been worked out yet, as the game is still in an alpha stage). Petroglyph obviously doesn't want to lock players into one playstyle, so the top of the game will be reachable through either mode, or a mix of both.

Another interesting addition to the game is an in-world social lobby, so you actually sign in and control your character while browsing around the game's stores, game modes, and friends' lists. That might seem gimmicky, but done right, it might provide a new layer to the metagame, and Petroglyph says it might eventually enable you to do things like trade dropped items. "We have support for player to player trade," Flock confirmed. "We'll probably have a more advanced feature for that post-launch."

Gameplay seems similar to most other MOBA titles, with two glaring exceptions. Like LoL, Petroglyph has chosen not to include "denying" in the title, though they "could definitely do scenarios down the road that introduce creep denial." And each map has a structure called a Relic with a brand new function. "You don't have to destroy them, they're not crucial to taking down the shrine," says Flock. "But if you do take them down, they're going to spawn what we're currently calling a megacreep."

The megacreep is a super-powered minion that can do a lot of damage -- but offers the other team a chance at a bonus. "If they're smart, they'll go and head that thing off and kill it, because it gives you a lot of gold and a lot of experience." Just like League of Legends' Baron Nashor, choosing when to summon and kill the megacreep on either side can make a lot of difference in the game.

And Petroglyph has more plans for extra modes, most likely coming after launch. "There have been talks about doing games as large as 10v10," says Flock, "of doing sudden death matches, or of doing 10 vs. the environment -- so raid style encounters." Duel maps are another possibility (though the game won't be balanced for dueling, Petroglyph figures players will do it anyway), and a variation of the standard Dota map was described to me that had two bases in the middle of the map with three lanes circled around the outside, instead of the standard setup of three lanes between two bases.

Petroglyph certainly makes it sound like they have some interesting ideas about the MOBA genre, and since the game is set up as free-to-play, it won't cost much to see how it all comes out. The title is currently in a Friends and Family alpha, and is set to hit beta in the next couple of weeks or so, with a release expected later this spring.

This article was originally published on Joystiq.