Setting: The world is under attack by aliens. All nations of the earth unite to X-Com together and form in a Komandobunker recruits and start operations.
It is expanding its base, forming soldiers from classes: Sniper, Medic, Heavy Weapons, storm, Mec (each class has their own skill trees), secures attacked towns and attacking landed UFOs. Until you finally found a way has effectively hit back!
Absolute buy recommendation!