If there was a Criterion Collection for games, this would be it. Not much in the way of AAA mega-budget blockbusters, but a whole bunch of best-in-genre classics from mid to small-scale studios.

While you could technically play some of these games solo, you probably shouldn't. These are built for group multiplayer through-and-through. Bring a buddy or three and you'll have a grand old time.

Games that'll last you an eternity. Once you're done with the vanilla campaign, there's a massive Steam Workshop (or other repository) waiting for you with more content than most will ever play.

Spent all your cash on a gaming-spec PC? Here's some great games that won't cost you a penny. Mostly freeware, but some donationware and especially generous F2P stuff too. Game responsibly!