Maelstrom is a real-time strategy game that takes place in 2050, on a savage future Earth. After an ecological disaster the two remaining human factions wage ware against vicious alien invaders, and each other, in a desperate struggle for survival. The factions are The Remnants (low-tech resistance fighters using conventional weapons), The Ascension (highly intelligent, logical, and ruthless exploiters using high-end futuristic weapons) and the alien race Hai-Genti (aquatic life-forms using bio-engineering as their main weapon).

Terraforming and influencing the elements are important parts of the gameplay. By freezing rivers, creating tornadoes or forming a mountain range players can transform their defense position. Hero units can be controlled directly in a third-person view. Six players can play in several online multiplayer game modes. The singleplayer part consists of 3 campaigns, for each of the factions.