In a nutshell, Java version game is built for is BROKE, and the used JavaFX version is apparently abandoned. Current java versions will cause infinite null pointers while running jar version of the game, and will make game abysmally slow if it even manages to run.Me aswell, search the thread. Might find some help there, otherwise wait for exe.
Basically, only expect the exe version to work anymore, unless you got an old as hell pc with the correct java and javafx already installed.