Haha, actually the space these were recorded in was quite bad! A drywalled classroom (luckily with high ceilings). My "secret", I guess, is a stereo pair of Rode NT1-A's. I'd put them on anything imagineable. I don't understand how damn good they sound, but they do! Now Rode has an even better version of the NT1 (it's jet black too), that I really want to get at some point.
It's actually very very basic recording stuff... just a spaced stereo pair of NT1-A's, like 2-4 feet apart from each other, high up pointed down towards the sound source, then a close mic.
The secret sauce is, of course, good convolution reverb. I swear 90% of how people perceive sample libraries is the reverb used in the demos. Convolution reverb well used is the difference between realism and flatness. A little white noise/hall noise stuck in there is no bad thing either.
My background is exactly what you hear... game music. Although I've dabbled in everything from 3D design to tutorial writing, game design, and more.
If you're around in a few months, I plan on releasing all of these instruments soon. :)