If given an unlimited time horizon I am sure I could invest myself completely in one tiny niche of video game development and run out of time on earth before I found the solution to every problem within that niche.
This is also known as re-inventing the wheel, and is to be avoided, whenever possible.
I did not think such a game.. could be programmed in a JIT compiled and managed language like Java and C#.
On resource-rich modern computers, you can write wonderful software in almost any language. Remember, most of your code isn't extremely time-sensive to begin with, and even when it is, the algorithm is usually more important than the language. High-level languages can help the programmer complete a project more quickly and with fewer bugs.
From what I understand Unity is a primarily visual development medium with programming access only at the scripting level.
It supports C#, which you already noted is a programming language. Also, with Unity Pro you can plug-in C/C++ when you really feel you must.