C# is mostly for web, not games. Python too, and Java I think.
I would suggest starting off with C++ as your base core, I mean most languages are based off of C or C++, like Java.
Erm, the three languages you said were for web are mainly used offline. But yeah, you are right about a lot of languages being based off of C/C++, and that none of those languages really has any good place in gaming (for anything large, anyway. maybe C#).
Why anyone cares about or wants to use object-orientated programming at this point baffles me. I'm serious though, it's not just stuff talk, why do you want to learn OOP in the first place?
From my experience, OOP is much more logically sound in programming than functional programming or other styles. The common use of languages with class or OO implementations such as C++ or Java demonstrate coders' likenesses towards OO.