3 Will the game come out on vulcan? (because its coming after directx 12)
Why do you ask?
Because of old computers or low spec computer with APU only
It doesn't work like that.
-it's irrelevant for such a small project whether it will be written in OpenGL or Vulkan - Krom makes the game himself, it will take him forever anyway, and you want him to add an extra year (that's an estimate) for something that has little importance for the performance of the game. Why? See next point.
-you can see how KaM needs a lot better CPU than GPU. This will not change even if it'll be a proper 3D game, the game's visuals will not be at the GTA level or something; also, the game simulation takes a lot of CPU power. If a low spec computer has a shitty CPU, it will be the main problem. Any APU is good enough for KaM nowadays (never had one myself, but I have an Intel card which is more than enough, an AMD is even better)
-there's already lots of work on the current OpenGL part, why waste it
-Vulkan is supposed to bring improvements to big and complicated 3D games
-Vulkan is mainly targeted at game engine developers (think of Crytek, Source, Unity3D), who have the resources and people to write highly optimized code.