In order to explain Grav I need to refer to another game: VVVVVV
I really recommend the game, it’s funny and it has great music. Really, give it a try.
The Super Gravitron is an arcade game inside VVVVVV, you can access it by entering the Secret Lab. It looks like that:
The point is dodging the blocks that appear across the screen and stay alive as long as possible!
Grav is pretty much a clone of that:
The idea was to add more sequences, games modes, etc. But I got tired of it and never finished it, though it’s totally playable and online highscores are working, so you can give it a try and have some fun:
It may crash some times but don’t worry ^^