Dear (?) Alabie,
First, “Just stop going against the grain.” - its usually the slogan of all the blunt, coward, weak people. Not just in the case of technology, but at all aspects of life. Please forgive me for not accept your shameful advice. In fact I feel even more offended by it than by Warhorse Studios cheating the 6 euro (or maybe all the 24 euro?) out of me. Please forgive me that I consider myself better than this attitude.
Second, there is no such thing as a gaming operating system. Every game works on specific operating systems, and people simply choose from the games that are supporting the os they are using. You need this information before buying a game. Linux support is a criterion for me when deciding on buying a game or not. So simple. I wont buy any games which run only on windows, just as I wont buy a book written in a language I cant read and have no intentions to learn it.
Third, business works like this: the vendor describes the important characteristics of their goods and services. I decide if I buy it or not based on that information. If that information turns out to be false by mistake, I claim for refund, and if it turns out to be deliberately false, I can even consider to sue the vendor. The platform was considered important apparently, they stated many times this game will run on linux. Upon this information did I decide to buy it. They stated the beta will run on linux. Upon this information did I decide to pay 6 more euro to upgrade from soldier to knight. Of course I was not buying the game, but I was buying their efforts to make it as they stated. What happened next? They started developing the game not supporting linux. It was their deliberate decision not to follow their campaign statements, not an unforeseen error.
This is the case that they were cheating money out of me by deliberate lies. It is not in the category of mistake, it is in the category of crime. They were intentionally causing me loss by stating lies. So simple.
I hope I could help you understand.