Looks interesting in the screenshots and poking around in the .jar file but it wouldn't run for me. I have openjfx installed. Let me know if you get it fixed to run on Java 11 and I'll try again.

java -jar Liam.jar Exception in thread "main" java.lang.NoClassDefFoundError: javafx/scene/media/AudioClip
    at main.engine.ui.SoundManager.loadSoundEffects(SoundManager.java:37)
    at main.game.Game.loadResources(Game.java:166)
    at main.game.Game.<init>(Game.java:85)
    at main.game.Game.main(Game.java:69)
Caused by: java.lang.ClassNotFoundException: javafx.scene.media.AudioClip
    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:583)
    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
    ... 4 more

java --version
openjdk 11.0.3 2019-04-16
OpenJDK Runtime Environment (build 11.0.3+7-Ubuntu-1ubuntu218.04.1)
OpenJDK 64-Bit Server VM (build 11.0.3+7-Ubuntu-1ubuntu218.04.1, mixed mode, sharing)

https://stackoverflow.com/questions/56848305/java-lang-noclassdeffounderror-when...