A cardiovascular take on QWOP, the running simulator (http://www.foddy.net/Athletics.html). A separate keyboard key is assigned to every chamber of the heart and each lung. Keep the heart beating at a steady rate and get oxygen to the body or risk passing out.
U, I, O, P are mapped the four chambers of the heart in the order in which they beat. Each chamber lights up when it contains blood; red if the blood is oxygenated or blue if not. Mid-beat, after the U and I phases, the blood-flow passes through the lungs and oxygenates... unless you forgot to breathe. Once the heart-rate is high enough for jogging and exercise, lungs come into play and breathing must be triggered manually.
Keyboard mashing works but is discouraged, it is the equivalent of a cardiac arrest. Just saying.
The Unity webplayer can also be found here: http://www.reinot.com/heartQWOP/