Maelstrom is set in 2050 in a post-apocalyptic future following an ecological disaster which results in much of the planet's submersion, as well as the subsequent nuclear holocaust over the remaining resources. Most of humankind has taken refuge beneath the surface, taking shelter from a long-standing war between the guerilla-warfare Remnants, and the hi-tech Ascension. In the midst of this war, an alien race facing extinction, known as the Hai-Genti appear, quickly flooding the land and slaughtering Remnants and Ascension alike.
The game utilises a lot of the technology used in KD's previous RTS game, Perimeter. Features such as terraforming and weather control are so far unique in the genre, and are said to be core to the gameplay. In Maelstrom, you can also control the hero units directly, in third person perspective.
Maelstrom's gameplay requires players to construct bases while harvesting resources in order to fund production of various units as well as construction of other structures in order to aid the player's efforts to defeat the enemy. Resources are not uniform between factions and are referred to by different names, but are functionally identical. The three main resources are obtained from Survivor compounds, water pumps and the Sun.
Source: Wikipedia, "Maelstrom (video game)", available under the CC-BY-SA License.