[H] Fistful of Gun serial [W] Gurumin serial

I'm cool with the dev making Fistful of Gun so he keeps throwing serials at me to get more people to test it before it comes out at the end of this month. But he's given me so many that I've already given one to all my friends who are interested, and now I'm sitting on a spare. I like falcom games so I'd like to try gurumin, but I didn't want any of the other games from that humble bundle. I figure since my game is just a serial key, exchanging it for another serial key would be fair