"Thinking outside the box" is something developers say a lot, but all too often in these recession-hit, creatively moribund times, the phrase translates to "new AI behaviours" or "Horde Mode 3.5". Enter Battleblock Theater, a deeply macabre and triumphant 2D platformer from Castle Crashers developer The Behemoth which does, in fact, think outside the box, despite being made almost entirely of the things.
The action begins when your party of pint-sized, waggly armed sailors shipwrecks on an island run by sadistic cats, who force them to compete in an endless array of gladiatorial trials (that's 450 to begin with, plus whatever you create using the remarkably accessible and controller-friendly level editor). An oddball narrator - think Bastion's Rucks with a hefty dose of the Joker - takes the minutes, greeting untimely deaths with shrieks of "Goodness GRACIOUS" and launching into madcap soliloquies during the cutscenes that break up chapters.
The writing is occasionally abrasive, too self-aware for its own good, but often hilarious, and while lines do repeat, there's variety enough to justify donning some headphones. Still, you might want to sit through a few of the trailers before committing to a full playthrough. This chap won't leave you alone for long.
Battleblock Theater's story mode is split into worlds comprising 12 levels plus a boss level, and the goal in each is simply to gather enough gems to open the exit door. Gems are also used to buy character skins at gift shops, a superficial but predictably addictive pursuit; more enticing are the yarn balls which can be traded with feline wardens for black market weapons, like grenades, Hadokens that fall upwards, mines you throw like Frisbees and a vacuum cleaner, which can be used to suck up enemy ordinance. Add these to the (temporary) power-ups, which include jet packs and wings you flap by tapping the jump button.
It's a familiar assortment, and so are the blocks themselves - ice blocks that'll slide you into laser beams if you run, cloud blocks that can be jumped through but somehow support your weight, platforms that rise when you stand on them, and fans that either pin you to terra firma, or propel you into ceiling spikes. Battleblock Theater's scintillating genius is partly a question of how these old devices are perverted - in a cheeky revisiting of Mario's infamous burned-bottom leap, lava blocks serve as bounce pads rather than hazards, and crumbling blocks set off their neighbours too, cue some smart puzzles involving chain reactions.
Mainly, though, it's in how they're combined. If modern games development is increasingly about conjuring the maximum gain from the minimum resources, Battleblock Theater could be Xbox Live Arcade's greatest stage magician. Like Rayman Origins, it's an intrinsically nostalgic experience that nonetheless refuses to get old. One level might call to mind the hectic pace of vintage Sonic the Hedgehog, as spring-loaded flippers conspire with teleportation tubes to fling players into troughs of shallow, fatal water.
Then you're plunged into something redolent of Super Meat Boy, an alternating sequence of conveyer belt platforms and sawblades, with a grenade-throwing goon at the end for good measure. Later: a trip through a cloud of ponderous furry dirigibles, dodging heat-seekers spat out by an indestructible toy robot. Subsequently: an elaborate spatial puzzle where you deactivate lines of holographic cubes to drop a paper boat into water, opening the way to the exit door.