Around each stage you'll find great sloshing lakes and waterfalls and rivers of cool blue water, as well as searing red lava in pools, flows, sputtering eruptions and veins in the rock. You'll find them, and you'll create them too - shooting away rock plugs and barriers to direct the flow of each fluid around the level and make the caves navigable in the way you want. When water and lava meet, the lava cools and forms a rock crust which can be blown away.
All this is important because your craft's shields are depleted by heat as well as enemy attacks, so steering too close to the magma for too long - never mind touching it - can cause it to overheat and explode. Conversely, plunging it into water cools it down, effectively restoring your health with an immensely satisfying hiss of steam. You're getting the idea; water is good, lava is bad, and you need to control the flow of both in order to ensure the triumph of good, sweet H2O over all that angry liquid rock, thus clearing passage for your ship to the stranded explorers and the exit.
Using missiles to clear rock and create new paths is the simplest way to do this, but there are more tools than that at your disposal. Huge barrels of water can be found, picked up, dragged and dropped in a violent explosion of cooling liquid. In another level, shooting away a particular piece of rock reveals a giant sponge, which promptly falls into a reservoir and expands as it soaks up the water. The sponge can be grabbed with the grappling arm and trailed behind you, spilling a constant stream of water as it goes, acting as a fire hose that creates bridges of rock across lakes of lava, or dams that you can blast away and reform, and blast away and reform.
It's hypnotic to watch and experiment with, and although there were fairly obvious set solutions for each of the levels I played, the heavy, slow-motion dynamism of the fluids means they never play out exactly the same way twice. There's obvious room for less scripted, more creative play as well, if Q-Games chooses to embrace it.
Regardless, PixelJunk 1-4 is an elegant, exciting and novel game design that looks forward as much as it does back. There's a perfect harmony and balance in the way the clash of hot and cold temperatures is used as both the health mechanic and the principal physical interaction in the game, for puzzle-solving, strategy, navigation and combat. The game hangs together beautifully, is fun to watch and gratifying to play. It's on its way to being the best PixelJunk yet.
All it needs now is a title. Q-Games will be opening this up to fans, hosting a competition to name the game on its website. Good luck. Doing 1-PixelJunk 4 justice in one word won't be easy.
PixelJunk 1-4 is due for release on the PlayStation Network this summer.