1) Sure there is
1) Sure there is…..lots of companies make cross platform GUI install packagers http://bitrock.com/products.html
I have seen lots of commercial windows and linux software use the exact same installers. And all the games that run on linux today including all the commercial ID Games have zero problems. Installing games is EASY on Linux, it juts gets put into /usr/local/games.
2) OpenGL + OpenAL/SDL == DirectX and BONUS…your stuff is already ported to about 4 other platforms for the same effort you would have used for using directx and be stuck with one crappy OS for all your effort.
Economically speaking…DirectX is a WASTE of money and resources. You could get an end product that you could market to a much wider audience for no more costs if you avoid DirectX.
Only Microsoft nubes or fanboys don’t see DirectX as a totally bad idea for a software development tool when perfectly good alternatives exist to provide more potential revenue for the same work.
3) 90% counts total marketshare including business computers which DONT RUN GAMES. SInce that 90% includes 99.999% of business computers, the HOME MARKET(where games are actually purchased) is probably closer to 20-25% NON-WINDOWS(maybe even higher for new sales with the current Mac trends) in order to bring the overall marketshare down to 90. Eg: Business 99.999% + Home 25% = overall 90%.
Wanna give up 1/5 to 1/4 of all your potential sales profits if your an investor in a game development?