In this game you're Darius Mason and you have to save planet Mars and its inhabitants from the alien invasion which involuntarily and tricked you started. In order to do so, you must fight your way through hordes of aliens. You have few bosses there, too. You must use your arsenal composed of basically your magnet gun and all sorts of weaponry. You can upgrades skills and repair bridges and other stuff.
Sadly, it's too short and not a lot of variety in there. It's pretty straightforward. I must mention that I replayed it on my console to see if it's different.