"Robocalypse: Beaver Defense is a tower defense video game developed by Vogster Entertainment for WiiWare, and a follow up to their Nintendo DS game Robocalypse. It was released in North America on May 31, 2010 and in Europe on June 4, 2010.
The game revolves around a mutated beaver's campaign for revenge against the player. Like other tower defense games, players place defenses around their headquarters in order to sorde of robots. In addition, players can directly control a hero robot of their own in battle.
The game was originally slated to support online play for up to four players, but this was later scrapped for the final release.
Source: Wikipedia, "Robocalypse: Beaver Defense", available under the CC-BY-SA License.