Monster Madness Online is a free-to-play multiplayer shooter that pits players against a Martian invasion of a suburban town. All of the adults have been abducted, leaving teenagers to be the sole defenders of our home soil. Players will go on co-op missions to fight the monsters with an optional roguelike mode for those who prefer the hardcore life or jump into 16-player PvP battlegrounds.
The game also features the option for players to set up their own servers, create their own mods, and whip up their own levels. It offers crossplatform play between PC, Mac, Linux, iOS, Android, Web Browser, and Windows Phone 8. Players can register for the upcoming beta on the site as well.
[Thanks to Mehighlow for the tip!]