Age of Zombies is free at the
Edit:
Actually there are some more games free at Amazon today
Zombie Highway (No Ads) by Auxbrain, Inc.
Get them all fromSlender Man! Chapter 1: Alone by Digital Code Works
Ghost RadarĀ®: CONNECT by Spud Pickles
Greedy Spiders by Blyts
Zig Zag Zombie HD (Kindle Tablet Edition) - Zombies, Vampires, Ghosts, and More! by Part Time Evil, LLC
Zig Zag Zombie by Part Time Evil, LLC