"just don't bother trying" I'm one of them. :/ Exported Windows only, but I was busy.
Guess it should be a condition too for next jam (Win, Mac, and Linux at least), but I'm not sure if there can be some problems between different OS-s. I know HTML5 is a mess sometimes. Also devs can't test the game on OS-s they don't have.
I exported to all platforms (excluding mobile) but it is kinda of a "use at your own risk"(still, better than no export at all) :D anyway, imo i value much more a dev that at least tries to make a game cross-platform than one that only makes it to one platform ;) (an example of this behaviour of mine is that i only spend my money on games that support linux)
EDIT: for me HTML5 works fine on firefox/linux
Anyway, good luck :)
