Unity uses C# for a certain layer but the engine itself isn't C#. They also do some work for ammortized multi frame GC. That said, there's tons of games writte

Unity uses C# for a certain layer but the engine itself isn't C#. They also do some work for ammortized multi frame GC. That said, there's tons of games written in less than optimal languages for major portions of the game, like Naughty Dog games in the PS1/PS2 era used a lisp based language for a lot of things