Easily one of my top 5 favorite games of all time, and top three co-op games. Don't play it too often these days, but always have a blast every time I come back to it. Even solo play isn't half bad, but I would heavily recommend grabbing at least one other friend to play with. The difficulty is pretty intense, so I would say at least watch a let's play of a level or two to get an understanding of what to do, but don't ruin the experience by playing through several levels solo then bringing in a friend to play with you, try to learn together, just know some of the basics of the game (especially the terminals).