Game companies generally use C++ because they need to interface with existing C and C++ library code (at least at the engine level). C++ also allows for various low-level optimizations when such things become necessary, such as resorting to inline assembler or stashing flag bits in pointers.

That's not to say that other languages aren't capable of these things, of course.

(I spent seven years working for EA, and I contributed to EASTL while I was there.)