Geisterblut is fucking nuts. Being “fucking nuts” appears to be its raison d’etre—its final screen, which you can reach in just a minute or two, hammers this home—but it’s not “trying to be fucking nuts” in the manner of, say, a Russell Brand bit. It is, rather, a free-jazz skronk, a noisy freakout of a videogame, and if I’m being a bit vague here that’s by design. It’s no fun to spoil an act of improvisation.  Designed by nuprahtor for the game jam Ludum Dare 32, the game is ostensibly about hunting for ghosts. I’ll say this: you’ve got a gun,…