Undertow features a 15 level campaign for single-player or co-op and two robust multiplayer modes for up to 16 players. While many of the maps have level-specific goals, the core gameplay of Undertow centers on this maxim: Kill as many enemies as you can and stay alive for as long as possible!
Players select their race (Iron Marine, Nemoidian, or Atlantian) and unit type and are then launched into battle. Each of the three races features four unique, upgradeable unit types ranging in ability from the fast and agile to the large and powerful. Players have the ability to unlock and purchase unit upgrades as they acquire points. Each unit type has three levels of permanent upgrades.
Through conquest-style battles, players obtain points by killing enemies, accomplishing team goals, and taking check points. Points and a variety of power-ups can be used to further upgrade unit abilities. In addition to the core game, additional expansions will introduce new races, unit types, maps, and bonus achievement points.