Dollar for Dollar the best $5 I have ever spent on gaming in my life.
So here are the basics. You move with one analog stick. You shoot with the other. You use you "bombs" to clear the screen (no points for what you kill) with a trigger. All the ememys move and react to you differently. For instance the green diamonds will just follow you slowly, the purple squares will follow you but when you shoot them turn into smaller squares and the crazy red pac man thing will attack you and you cant shoot it head on. The whole point to the game is to survive and kill the everything on the screen.
This might not sound very interesting, but this game is extremely fun. The first time you move through some hectic stuff and come out alive you understand what you are capable of. The more you play, the better you get. This game is a true skill based arcade shooter in the best sence of the word. Awesome. A must buy. And at only 5 dollars the best value in gaming.