Here is the full list of all 17 Of Tanks and Demons III achievements worth 1,000 gamerscore.
Beat the first boss
Complete five levels
Beat the second boss
Complete ten levels
Complete twelve levels
Beat the final boss
Purchase a THUNDER
Purchase a HELL BUSTER
Purchase a RED SHADOW
Purchase your first upgrade
Purchase all upgrades for one tank
Kill 72 monsters
Use boost 60 times
Collect 50 photons
Collect 100 photons
Collect 150 photons
Don't leave a level after it ends