Indie games can be a source of endless entertainment. The best of them can give you a great experience with interesting but fun mechanics, all with graphical requirements and price much lower than their AAA brethren. When a game isn't under pressure to be seen as "mainstream," game designers are free to unleash their creativity and make something that doesn't have to be marketed to as wide an audience as possible. They also don't have to make it easy.
It's easy to make a hard game, though. It's not as simple to make a hard game that doesn't feel cheap or unfair. When a game pulls it off, though, it can be an incredibly rewarding experience. Just ask anyone who's played Dark Souls. (And don't mention the Bed of Chaos.)
With that being said, here are five of the most difficult-- in a good way-- indie games you'll find on Steam right now.