Just practically edit the game controls to meet those of the controllers.
See the thing is the game cant be altered, or changed. So current progression on putting this game onto another device is low. At the moment the game itself is the highest platform (PC and Mac) it can be right now. So really you can't alter the game for anything else without the coding that Kovu has withheld from staff.
You wouldn't exactly need the source code as the controls file is a .cfg, you can open it in notepad, and with the proper programming experience you could transfer controls. I have done it to multiple games, it's not really that hard, and I don't mean to be rude if I sound it, but yes, it is possible without the source, you would just need to place that file up for download and ask users to replace the original "controls.cfg" file.
But as for a mobile version, yes, you can't change it without the source.