In Risk of Rain, time = difficulty. The longer you play the harder it gets, do you tear through the levels as fast as you can or do you spend time collecting some of the many ability granting artifacts? With randomly generated levels, giant bosses and just one life. How far will you go?
The graphical style and music illustrate a fantastic setting, the soundtrack captures very well the feeling of loneliness the player adopts, the monster and item logs are very interesting, there are many characters with diverse abilities and strengths, the gameplay is very smooth and exciting, the difficulty is very present but not unfair, and the game is long enough but also short enough that it's easy to play over and over again.