Geometry wars was an accident. The game was a minigame which was part of Project Gotham Racing 2 for the Xbox. Eventually when the XBox 360 was released, Geometry Wars was brought back as Geometry Wars Retro Evolved. This was the first time that I played the game. It is of the twin stick shooter genre, where you move with the left stick and aim with the right stick in a top down view with all manner of enemies coming after you.
The game is incredibly fun and has that one more try factor down pat. Dimensions is just as good I'm sure, and its coming to iOS. Twin stick shooters have not been very successful on the tablets and phones, mostly because the controls aren't there, there is no tactile feedback and you're thumbs cover the screen making it difficult to play.
The game comes out tomorrow, and should be available in some locations tonight. The thing about this that's good? $5, No in app purchases, you buy it, you get the whole game.