I picked up Phoenix Point because I was feeling that XCOM itch and knew if it wasn't this I would start a Long War game of XCOM2 which would probably take 2 years to finish if I did at all.
Far Cry 5 is $6 and though I'm not particularly tempted I've heard good things.
Mad Max is $2 and if you haven't played it I would say it most certainly a bargain at that price. It is fairly boilerplate open world where you take towers and bases to gather resources for upgrades and eventually unlock tougher and tougher zones. The vehicle combat is really the standout and your car is the star of the show. Just tearing around the desert is fun in itself. Taking caravans is particularly cinematic and satisfying to eventually bag one that you just weren't quite able to before your latest upgrade. Unfortunately the base assault and dismounted fighting is pretty forgettable with batman arkham-style auto-target with quicktime blocking that doesn't change very much as you unlock new abilities. My 2nd favorite open world game after shadow of mordor/war.
The downside of using key sites like GMG is that if you don't like the game for whatever reason, you can't refund it on Steam. I learned that the hard way by preordering Guilty Gear Strive, and when the game fucking sucked balls and they started censoring the word Taiwan from the game... I couldn't do anything about it.
That is a very true risk. I usually only buy from there when I'm certain I'm going to enjoy it (which is the only way I'll buy a brand new game anywhere near full price) or its on such a deep discount I can consider it a lost gamble if it sucks.
Though GMG is pretty good on refunds themselves if something else comes up. More than once I've had a game where they legit ran out of keys and couldn't give a lot of people their game, and they just refunded us no question on it.