The game is essentially Defense of the Ancients-Allstars and the Warcraft III mod's full 100+ character roster is being brought over in its entirety. The gameplay will also be unchanged.
"Our first reaction is to assume that [design elements are] there for a reason," project lead Erik Johnson explains. "IceFrog is one of the smartest designers we've ever met. He's made so many good decisions over the years in building the product. He virtually never makes a decision that doesn't have some reasoning behind it and a way to pick apart the logic behind it."
Dota 2, as a Valve project, will naturally use the Source Engine, which will get improvements to the global lighting engine along with true cloth simulation. Dota 2 will also gain integrated voice chat from its move outside of a Warcraft III mod. Dota 2 adds AI bots for disconnected players and for practice games, but there will not be a singleplayer campaign.
Steamworks will also be getting an overhaul for Dota 2 with support for in-game rewards, which can be earned by participating in the Dota 2 community. "Everything from unlocking new skins for your favorite hero to getting a unique title for writing a strategy guide is on the table," explains GameInformer. The improvements to both the Source Engine and Steamworks will be available to third-party developers after the launch of Dota 2.
Valve will also be adding a coaching system to the game, which will allow skilled players to log in as "coaches" and earn in-game rewards for highly-rated coaching, as voted by the students. A coach will be able to see the student's screen and give them tips and pointers over voice-chat.
"IceFrog was one of the smartest people we've ever met about doing that, and he was doing it with both hands tied behind his back, so to speak," said Valve founder Gabe Newell. He likens the future of Dota 2 as a "service" to that of Valve's Team Fortress 2. "Valve is going to keep building software around Dota and around the community and around Steamworks for Dota, but we're also going to build this system where the community can bring service to each other and be recognized for it," adds Johnson.
Dota 2, by all accounts, is a feature-laced port of the original DotA-Allstars to the Source Engine, not a new game. S2 Games (Heroes of Newerth) and Riot Games (League of Legends) both operate DotA-alike games, with HoN being much closer to the original DotA. League of Legends is quite different within the DotA sub-genre and is also free-to-play, supported by micro-transactions.
Valve's Dota 2 will be released in 2011 for the PC and Mac. Interested parties can find a lot more information over at Game Informer.