Answer 1

Basically games like Temple Run, Subway surfers are designed using Game Engines!
When you go with just coding , it will become complex regarding the gameplay, graphics and also difficult to organise the code!
So Game Engines are used.

Programming languages used entirely depends on which game engine you are using!

Game Engines - Programming languages

Unreal Engine - C++
Roblox - Rbx.Lua
Unity - C# and js