Spelunky is a hard (but fair) rogue-like platformer with endless replayability.
Simple but addictive yet very challenging,
Every death you have will seem unfair at first but can be avoided.
The first time you beat the boss it's one of the most satisfying things you can do in a platform game and when you beat the secret boss you will feel like a platforming god.
But the challenge doesn't stop there, you have no gold runs, speed runs, daily challengs and if your a real masochist you can try to do an eggplant run.
One of my favourite games of all time and easily worth full price.

10/10 would recommend to anyone looking 4 a good challenge or a great platformer.