Sentry is a co-op shooter about laying traps to defend your spaceship
Tower defense games aren't my thing, but the exceptions are those that embody you in a particular character on the battlefield, Orcs Must Die-style. That's what first-person shooter Sentry does. Sentry is an "action-defense" shooter in which you're protecting a spaceship from waves of aliens, alone or in co-op, by placing traps and blasting heads. You'll find the trailer below.