Wow.

Question regarding index access: There are tons of for loops with player[k] occurrences and similar. Personally I would create a local variable and prevent further index-retrievals.

Is this worthwhile or would a compiler optimize the array-index access away? Or maybe subsequent uses of the same index are cached by the cpu? Does someone know?

That's a micro-optimisation that's absolutely worthless. Even if you do pay the cost of indexing an array every single time, that's just a single instruction to fetch the address. The compiler is absolutely capable of caching the indexing for you, either in a register or on the stack, if it deems it worthwhile.

One reason you might want to use a separate variable would be to prevent indexing mistakes, like using i instead of k by mistake in a context where i is a nested loop's counter. But apart from this and other "to make it easier on the human" reasons, there's no point in caching that in a variable. Now, if you were writing Python on the other hand...

Holy batman. Now this is officially the worst piece of code I've ever seen in my 15 years of programming. This has to be generated... right?? I can't believe any human wrote this.

Grabs the eye bleach

It was written by a highschooler who made a 3D video game with decent physics and you're... criticizing him? Man, I'd like to see what YOU wrote in highschool.