How about these games?
Rainbow Six:Shadow Vanguard if you like AI teammates that can actually be helpful and FPS action. Little bit too short and easy, even on the hardest difficulty though.
FTL:Faster Than Light if you like space roguelikes.
Max Payne or GTA if you like either third person shooters or wide open sandboxes.
Rebuild is potentially interesting.
Wolfenstein 3D and Doom because they're classics.
Critical Missions:SWAT for Counter Strike on the go.
Breach and Clear for some tactical turnbased and realtime-ish action.
Organ Trail for the classic Oregon Trail experience, but with zombies.
These games are all "real" App Store games. They're not designed to exploit In App Purchases and drain your wallet(Ex. Candy Crush, Clash of Clans). Breach and Clear has IAPs, but you honestly don't need them and can do fine without.
There is also Payback 2:The Battle Sandbox(Free, but has IAPs) if you like top down GTA-ish action. There are bots for multiplayer.
