Risk of Rain is a 2D action platformer with roguelike elements where permanent death is a primary feature, Your goal is to survive as long as possible on a mysterious planet, with randomly spawning enemies and bosses.
Pro Time equals difficulty
It gets tougher as time passes by. That means by minute 40, you are playing at hardcore difficulty. This makes for an experience that is good for learning the mechanics as once you can not advance due to the difficulty you will die which means the game has to be repeated which help learn the ins and outs more and more each time it is done.