StarCraft II features the return of the three species from the original game: Protoss, Terran, and Zerg. Blizzard states these are the only playable races in the game.StarCraft II is also designed to focus more heavily on the multiplayer aspect, when compared to the original StarCraft. The changes include overall improvement in Battle.net, a new competitive "ladder" system for ranked games and new matchmaking mechanics—designed to "match-up" players of equal skill levels.[In addition, the replay function, which allows players to record and review past games, is being improved. Blizzard has also stated they have made some changes to the game that were suggested by fans.