I use Windows for some gaming. I believe that games are lot of work product and there should be option to have be paid. Linux is GPL. But is it not possible to have commercial games on Linux. Games are POSIX and MESA mostly I believe. You do not need to link with GPL code probably.
Even if a Linux distribution is free software, nothing prevent you to run proprietary/closed source software, if it is available.
So, game developers can freely (as in freedom) release games for Linux, also closed source games, and also paid games. (As far as I know, there are some titles out there).
I’m not a gamer, but have you seen Steam?
This is not advice, but it is not exactly that in my opinion. Copy left license (like GPL) have requirement to be able to get source code of work which links with GPL licensed library. But POSIX is international standard so you can use it, and MESA (3d lib for OpenGL and Vulcan) is MIT licensed. That means probably nothing prevents you from releasing closed source game for Linux.
This is correct. In fact, there are many closed-source games which will run perfectly well on Fedora Linux.
However as game developer you must wisely choose API to be not GPLed.I have been interested for example about Oracle DB on Linux. AFAIR Oracle commited some async io API to kernel to improve efficiency of RDBMS. What I believe is that if they use this API in Oracle Database it is violation of GPL license. Just my opinion, not legal advice.
It depends. Using a GPL components may mean your game engine needs to be GPL as well, but does not necessarily mean that you need to open source the contents. In practical terms, though, most game engines use MIT or Apache licenses which do not have a copyleft clause.
As for Oracle or other applications using kernel APIs, see Linux kernel licensing rules — The Linux Kernel documentation, which says:
The User-space API (UAPI) header files, which describe the interface of user-space programs to the kernel are a special case. According to the note in the kernel COPYING file, the syscall interface is a clear boundary, which does not extend the GPL requirements to any software which uses it to communicate with the kernel.
You must be right. Other way Andoid thing would probably be also violation of GPL. As Linus Torvard states, kernel security depends of ability of people to read source code. That includes license too.