The fourth PixelJunk game has the most basic and functional title since the first, but as ever with Q-Games' genre-hopping download series, things aren't quite as straightforward and off-the-cuff as the Kyoto developer likes to make out. Racers was a rhythmic, track-hopping reaction test rather than a straight racing game, Monsters was arguably the most highly-evolved tower defence game on consoles, and the purportedly restful Eden turned out to be a tortuous and maddening platformer.
Shooter might appear to be shrugging itself off as another twin-stick blaster, but in fact it's a game of exploration, collection and puzzle-solving as much as action - as well as being a hypnotic physics plaything, thanks to its spectacular fluid dynamics. It's about as laidback as this famously testing series has ever been.
Recalling the classic Thrust - but nowhere near as difficult - PixelJunk Shooter has you steering a small craft through tunnels and caverns, rescuing stranded workers in conspicuous orange hazard suits. In each scene (there are five scenes to a stage, five stages to a world and three worlds in total) you need to account for all the survivors to unlock a door and progress. You do this by grabbing them with a grappling hook or failing to avert their deaths, but you can only do the latter five times before it's game over. Your ship, however, has infinite lives.
That's the first sign that Shooter is going to go a little easier on you than the 2D classics that inspired it. The second is the supple controls, although this is hardly a complaint; your ship handles exquisitely, with just enough momentum to manage, and a boost if you point both sticks in the same direction. The third sign is that contact with the walls doesn't damage your ship. Danger, instead, comes from the cunningly-designed enemies - bats, organic turrets and burrowing, spinning living mechanisms, all of which seem to have crawled straight out of the dank caverns of a Metroid game - and from heat.
Sometimes you generate this yourself (holding down the fire button unleashes an overheating volley of homing missiles), but most of the danger comes from the environment. In the first world, delving into the bowels of a volcano, you encounter pools and spouts of water and magma. Proximity to magma overheats your ship, while touching water cools it instantly. Reservoirs can be drained and rivers diverted by blasting away at stone barriers, but the game starts to get really interesting when you bring the two into contact, cooling the magma into rock which can be destroyed. Your ship's grapple can pick up and drop explosive water bombs, or giant sponges which soak up water and then release it in a steady downpour, like a helicopter fighting a forest fire.
Huge bodies of fluid are flung around the screen, behaving consistently and believably as they hiss and sizzle against each other, while you puzzle and blast your way through these tightly-conceived little mazes. Don't be fooled by the plain cutaway graphics with their bright, simple blocks of colour; Shooter is a proper 1080p spectacle and an impressive piece of physics programming. It's also driven along smartly by some great music - a funky, dynamic collection of upbeat trip-hop in the Ninja Tunes style by High Frequency Bandwidth.