“Really? Seriously? There is absolutely no doubt that software makers, especially game makers ignore the Linux market.”
I guess it depends on which software makers you’re talking about.
One of the reasons I switched to Linux was because I was tired of proprietary software companies dictating what I could and could not do. I certainly don’t miss that. Open source equivalents do sometimes lack certain features of their proprietary counterparts, but they often include additional features of their own to make up for that.
For instance, while Linux may not have the variety of proprietary software that Windows does, every respectable distribution comes with comprehensive, easily extensible software repositories that don’t require you to sign up for a user account. You also get a package management system.
Lack of proprietary software isn’t holding Linux back. In fact, there’s nothing to hold back: it has already won. Linux powers Android, the world’s most popular smartphone OS. It runs on most of the world’s top supercomputers and many servers. It’s used in embedded devices ranging from Wi-Fi routers to automated vacuums like the Neato XV-25.
A better question might be what is holding Windows and OS X back from achieving such comprehensive market dominance. Aside from the desktop market, Linux has won.
Your successful linux examples are a primitive kernel running a JVM and two headless servers. Windows does a whole lot more than that but lately MS has reversed course and simplified (or dumbed down) both the kernel and their GUI.