Coupon/voucher works on most title sitewide and should stack with new Black Friday sales. Works in all region, including the UK, EU, and most Asian regions.
For our fellow Steam gamers visiting from abroad who doesn't want to fiddle with robot translation:
Use coupon code DECEMB-202014-GREENM on the following:
Use Coupon: 726B15-MPNMO3-FJLGSJ
Day 1 - Batman Titles
Works nearly site-wide with few exceptions.
Use coupon code GOS0EO-L1SK9P-HBBMO3 on the following:
Use coupon 53NSRB-GTOJQD-8WN7GJ on these titles:
Note: Coupon no longer stacks with certain title.
Final Fantasy Series: