Since the game REQUIRES libpng12 the game is unplayable on newer then 16.04 ubuntu since that was the last version to use libpng12 newer versions use a newer version of libpng. For example Linux Mint 19 which is based off of ubtuntu 18.04 uses libpng16 and thus you are unable to run Septerra core unless you also install libpng12 alongside libpng16. So it looks like you guys may be forced to update your games to play on newer verisons.

The "Linux" version is just the Windows version packaged with wine. Use a version of wine that works on your system instead of the one it was packed with, and watch your issues disappear.