At points, Orcs Must Die! made me angrier than Dark Souls, which has got to be some sort of achievement. A third-person take on tower defence that mixes trap-laying with simple blasting and melee combat, it's a deeply charming game with a difficulty curve that veers wildly and a toolset that's half pot luck and half brilliance.
You play an apprentice mage who's tasked with keeping waves of Orcs, Ogres and other beasties out of the 'rifts' in each level. Huge groups of enemies spawn from fixed locations and run along predetermined paths towards them. If too many get to the rift, you lose. To stop the horde you have an initially limited set of traps and personal weapons, which rapidly expands into a huge grab bag of troops, whirring blades and smooshing contraptions perfect for turning green mobs into pesto.
You're given as much time as necessary at the start of levels to scope them out on foot and place traps, identifying bottlenecks and environmental hazards that will maximise your weapons. Traps cost cash, anywhere from 200 glowing blue money points (they don't seem to have a name) up to thousands, and killing enemies grants from 10 to hundreds depending on toughness - all self-explanatory enough.
The first thing Orcs Must Die! gets right is the trap-laying interface. At each level's beginning, you select the traps you want to take in (these can be changed before the horde is unleashed), and then cycle through them with the bumpers before pressing A to place. Traps have certain requirements, for example whether they need placing on a wall or a floor, and bright green or red wireframes instantly communicate whether a certain position is going to work - it's simple, fast and makes setting up death corridors an absolute pleasure.
As for the traps themselves, they can be simple damage-dealers, slow enemies down, or bounce Orcs around into convenient pits of doom. A favourite is the arrow wall, which when triggered sends arrows shooting out multiple times that can absolutely nail through crowds - combine this with the tar trap, which slows down mobs, and the distance upgrade, which lets it trigger from further away, and you're really cooking. The spring trap, on the other hand, doesn't damage the mobs but can either fling them towards something that will, or simply be used to bounce a crowd back to the start of the gauntlet. Why not set up a load of spinning blade walls at the landing point?
Other traps work in concert with the troops you can spawn. These draw from the same currency pool, but have several big advantages. The first is that they attack the Orcs directly rather than waiting for them to walk by a certain position, and the second is that they attack frequently. The traps have a long reset time after each use, but if they're set up right, they do mega damage - so the trick on most levels is to have troops whittling at the crowd constantly, and certain uber-death spots that crush the remainder.
Everything is about building to this point. In each level's initial stages you'll have much more involvement with actually killing the Orcs and building up the war chest; the earlier crowds are smaller, and your various melee weapons are very effective. Personal combat isn't subtle, but it's a lot of EDF-style fun with elements of skill - the crossbow in particular has an expanding reticule that means either picking headshots from afar or spamming bolts up-close. Later, flame gauntlets let you chuck fireballs into bunched-up groups, and the best of the lot is the wind belt, which can be used to push giant clumps of enemies into pits and traps.