I've been playing Space Marine 2 during its early unlock period, and while it's a shame the campaign is balanced for co-op—expect a lot of objectives you have to complete while under attack and with AI allies who suck at keeping enemies off your back—it's still a blast getting stuck into hordes of tyranids. There are so many waves of them it's like a full degustation, and the finishing moves make it look like you're cracking open the shells of ornery lobsters.
One good thing about playing...