This game is currently a part of a HumbleBundle, and being ridiculously cheap, I decided to check it out. Its super fun. Kind of the stereotypical space marines vs. xenomorphs, but the gameplay is fun enough the theming doesnt matter too much. It has RTS elements -- one person elects to be the commander who has a top-down view of the game and can coordinate you team, build structures, upgrade weapons, etc..
https://www.humblebundle.com/The good thing is tons of noobs (like me) ("rookies" as the game calls them) are playing due to the sale, so it's a good time to learn the game. It also seems very similar to the original Natural Selection (which I never really played) so veterans wont be lost either.
Highly reccommeded!