We're Shaun Inman super-fans around here, as The Last Rocket [$1.99] is always somewhere near the top of games I tell people to check out. (The book on the game's development is also awesome.) Flip's Escape is hitting the App Store tonight (and might already be available if you're in a non-North American region), and I'm really digging this pseudo-sequel.
Gameplay is remarkably simple. You play as Flip escaping the (SPOILER ALERT!) explosion that occurs at the end of The Last Rocket. You collect stars, blast into warp mode, and pick up gems along the way which are used to buy all sorts of permanent upgrades and consumable powerups. Of course you can also buy these gems via various IAP options, but it seems exceedingly optional. What you're looking at here is just a super simple single button game done really well.
International App Store Link: Flip's Escape, 99¢ - Currently available in some regions, will be in the US App Store at 11:00 PM Eastern.