Carmageddon (it goes free occasionally, like on anniversary of the game’s release, I got it free, look for Carma Free on those days :D, there is also a demo available all the time): https://play.google.com/store/apps/details?id=com.stainlessgames.carmageddon
Crazy Taxi: https://play.google.com/store/apps/details?id=com.sega.CrazyTaxi
Afterburner Climax (actually not that good on the phone, but nice visuals): https://play.google.com/store/apps/details?id=com.sega.afterburner
Hungry Shark Evolution: https://play.google.com/store/apps/details?id=com.fgol.HungrySharkEvolution
Flappy Bird (fun time kill when you get the hang of it actually, but I think it’s taken down now!)
Ridiculous Fishing: https://play.google.com/store/apps/details?id=com.vlambeer.RidiculousFishing
Max Payne Mobile: https://play.google.com/store/apps/details?id=com.rockstar.maxpayne
GTA Vice City and San Andreas (not that I recommend playing these on a phone anyway, really only if you want to impress people, or for some reason you have no other console or PC to play these games on… which would just be sad, and hopefully you have some kind of controller to hook up to your phone… lol): https://play.google.com/store/apps/details?id=com.rockstargames.gtasa
https://play.google.com/store/apps/details?id=com.rockstargames.gtavc
^And keep in mind the visuals in these versions are really crummy compared to the originals, especially in terms of effects, despite the higher resolution, they look like real crap compared to even the PS2 versions
Air Attack HD (there is a free demo of this on the store, probably the single best quality and fun game I have played on phones, though I’ve only played the demo, it’s really good): https://play.google.com/store/apps/details?id=com.ArtInGames.AirAttackHD
Death Rally: https://play.google.com/store/apps/details?id=com.remedy.DeathRallyFREE&hl=en
Kingdom Rush and Frontiers expansion (even though you already mentioned them): https://play.google.com/store/apps/details?id=com.ironhidegames.android.kingdomrush
https://play.google.com/store/apps/details?id=com.ironhidegames.android.kingdomrushfrontiers
Brainium Solitaire (best solitaire app on Android imo, they have other games too, non-invasive permissions too): https://play.google.com/store/apps/details?id=com.brainium.solitaire