Q-Games' quirky PixelJunk series is trundling right along with its fourth installment, the specifically titled PixelJunk Shooter. I got to play around with a demo version of the game at E3, and found that while it's certainly got shooting in it, it's not at all the kind of arcade-style side-scroller that comes to my mind when I hear the word "shooter." It's quite a bit more original than that.
You control a ship that can hover, and can fly and shoot in any direction. You're responsible for flying around inside a bunch of catacombs and rescuing little people stranded inside with an extendable grappling hook-like device you can drop down to snag them with. There were some flying enemies here and there in the demo I played, and quite a few turret-like ones mounted on the walls. The shooting uses dual-joystick controls, though luckily the game does a good bit of auto-aiming for you, so the combat wasn't too frustrating what with the omnidirectional movement and all.
The really unique-slash-creative aspect of Shooter is its fluid dynamics, which it uses to simulate both water and lava in a reasonably realistic way. Both liquids slosh around inside pools and basins, and since some parts of each level are destructible, there are a lot of places where you can shoot out some rocks to cause one or the other to flow in a given direction. When water comes in contact with lava, it hardens into rock (which you can blow up), so a lot of the game's basic puzzle-solving revolves around figuring out how to get one liquid or the other where you want it to go so you can make a path to the people you need to rescue. It gets tricky since your ship can't get too close to lava for too long without overheating. You can always dunk yourself into some water to cool down quickly, at least.
Shooter has a two-player cooperative mode (local only; sorry, PSN junkies) that lets two people fly around in the same level. You can damage each other with your missiles, but on the upside, you can also use your grappling hook to save your buddy if his ship has overheated too drastically for him to fly on his own.
Q has a good thing going with the PixelJunk series, and Shooter looks like an entertaining addition to the series. The demo ended with a gigantic crab-like boss jumping out of the ground--though it cut to a "thanks for playing!" sort of screen before you could actually fight it--so there are certainly hints that there's more to the game than what was shown in the demo at E3. Here's a taste of the game that shows off the basic mechanics pretty well.