For some reason the song reminds me of 'In Time' from Bill and Ted's excelent adventure. If life and corpse create zombie then shouldn't either that or blood and corpse create a vampire?
Great game, brilliant original idea. If I had one complaint, and I don't, it would be that I can't figure out the secret upgrade, but no biggie I can still enjoy the game with out it. And to think I almost didn't play it based on the description