Let's be honest. As much as I love this game, I can't in good conscience give it 5 stars. Not because it hasn't provided me with unparalleled joy, but because even with a completely subjective review you just can't say this is a perfect game. I can't, for instance, even imagine playing it by myself.
But that's the beauty of the game. It provides that giddily enjoyable co-op experience that you just don't get in modern gaming anymore. And by co-op I mean playing with another breathing human being actually sitting in the room with you. It's the type of game that calls back distant memories of arguing over who gets to be the "blue guy" because you "always get stuck playing as the red guy." It's mindless, but it makes for some great multiplayer fun. You'd be hard pressed to find more quotable dialogue, too. When you're penetrating into a deep cave, fighting off hordes of giant nightmarish acid-spewing insect aliens, only to hear one of your cohorts complain about how hungry he is, you can't help but embrace the quirkiness of this game.
I mean, look at your character. He has a uniform that looks cobbled together out of a janitor's coveralls and old street hockey equipment. Your fellow soldiers always sound hopeless and on the brink of panic, unless they get distracted by their aforementioned hunger. You never run out of bullets and never run out of enemies. This game is a nostalgic oddity that I find irresistible.