Having just blasted pre-order bonuses , I would encourage you to consider pre-ordering Natural Selection 2. Why? Because it'll let you join in on the Alpha test when it opens on July 26, and you'll have special black marine armour whenever you play. Come on, black armour!
Natural Selection 2 is a class based team shooter with asymmetrical sides. The aliens are organic nasty things that break down doors and crawl on the ceiling, while the human side can build buildings and, you know, shoot bullets out of guns. You can pre-order it here .
Here's the content that'll be in the initial alpha: