Players face a huge and trap-filled dungeon that does not forgive a single mistake. You need a lot of speed as you go up, since the water level rises slowly but steadily, and will kill you if you get covered in water, meaning you have to start over from the beginning.
Apart from speed, Flood the Chamber requires a good dose of skills and accuracy, since most of the jumps are really hard to make. So much so, that one of the first games that this reminds you of is the (terribly difficult) I Wanna Be the Guy.
Flood the Chamber only has one, immense, level, which you have to beat in a single sitting. That said, the game can last a lot longer than you think, since its difficulty level will probably make you start over several times.