This is one of the other games I purchased for my iPhone and I'm happy to say it was worth the price tag. Minigore is an arena shooter where you control some guy in a boxed area who must survive against the growing hordes of fuzzy black Furbie things. Think of it as playing Left 4 Dead from a top-down perspective.
It costs 59p to purchase, it can be played in quick bursts or a long time if you're trying to beat your high score, the visuals are pretty, the learning curve is low and the touch screen controls actually work okay on it. Check out the Minigore website to see what it looks like in action, it's worth your 59p.