This voucher can stack with cashback/credit offers, which usually they don't.
My referral link if you don't already have an account (means we both get $2 credit once you spend $2 or more): http://www.greenmangaming.com/?gmgr=kucipixo
Some games to use it with:
Sine Mora (already 75% off): $2.00
Devil May Cry 4 (already 66% off): $5.43
Super Meat Boy (already 75% off): $3.00
Batman Arkham City: GOTY (already 60% off): $9.60
ArmA II (already 40% off): $14.40
Bastion (already 60% off): $4.80
Jagged Alliance Back In Action (already 75% off): $8.00
Pre-orders to use it with:
Tomb Raider (already 10% off): $36.00 + $1.00 cash back / $2.00 credit
DMC: Devil May Cry: $40.00 + $2.00 cash back / $3.00 credit
Dead Island Riptide: $32.00 + $2.00 cash back / $3.00 credit
Noticed the reason for why it stacks with cashback offers when it normally doesn't. Tomb Raider 2013 originally had a $10 credit or $8 cashback, now its only $2/1 so its pretty much the same price