One good run is all it takes... Just getting that one run is a grind.

It's Snake!
It's BreakOut!
It's free!
It's fun!

One of the best examples of design juicyness I've seen. It combines the intricate movement of Snake with the frenetic block hitting of Break Out and seizes it in a simple board where you're able to do lots with it. The mechanic works so well, it's a wonder how it took that many years to figure it out and provides different skins but only one track sadly.