We used the Vicious 2 engine
http://www.viciousengine.com/
The company that created it is really cool, and if you never played it, their game Eat Lead: The Return of Matt Hazard is a lot of fun
The credit is an Amazon thing, we have nothing to do with it. I'm not sure how/why it is happening, but if people who are buying our game get a nice bonus, I'm not going to complain :)
Blood of the Werewolf is available on Steam for $1 until May 24th. http://store.steampowered.com/app/260250
Total Biscuit reviewed the game this week as well, so you can see if it's your cup of tea. https://www.youtube.com/watch?v=5jv_hR5eoOw
Full disclosure - I'm one of the devs who made the...