Earn to Die 2
Earn to Die 2 is a driving game set in a post-apocalyptic zombie world. You must drive your card along abandoned highways littered with crates and boards and covered in zombies. You're awarded money for every zombie you kill as well as how far you drive, and that money is used to upgrade your vehicle allowing you to get further each time. Once you make it to the next garage you unlock a new stretch of road, and, every three roads you unlock a new vehicle.
I found this game while looking for a new casual game for my phone.