Just bought the game and experienced the same issue. Here are some details:
MewnBase Version: 0.43 macOS: High Sierra Version 10.13.5
$ java --version java 9 Java(TM) SE Runtime Environment (build 9+181) Java HotSpot(TM) 64-Bit Server VM (build 9+181, mixed mode)
$ java -jar MewnBase.jar Exception in thread "main" java.lang.ExceptionInInitializerError at org.lwjgl.glfw.GLFW.glfwCreateWindow(GLFW.java:1647) at com.badlogic.gdx.backends.lwjgl3.Lwjgl3Application.createGlfwWindow(Lwjgl3Application.java:442) at com.badlogic.gdx.backends.lwjgl3.Lwjgl3Application.createWindow(Lwjgl3Application.java:391) at com.badlogic.gdx.backends.lwjgl3.Lwjgl3Application.createWindow(Lwjgl3Application.java:379) at com.badlogic.gdx.backends.lwjgl3.Lwjgl3Application.<init>(Lwjgl3Application.java:108) at com.cairn4.moonbase.desktop.DesktopLauncher.main(DesktopLauncher.java:41) Caused by: java.lang.IllegalStateException: GLFW windows may only be created on the main thread and that thread must be the first thread in the process. Please run the JVM with -XstartOnFirstThread. For offscreen rendering, make sure another window toolkit (e.g. AWT or JavaFX) is initialized before GLFW. at org.lwjgl.glfw.EventLoop$OffScreen.<clinit>(EventLoop.java:37) ... 6 more AL lib: (EE) alc_cleanup: 1 device not closed</clinit></init>
$ java -XstartOnFirstThread -jar MewnBase.jar MewnBase: SettingsLoader: Creating default settings file MewnBase: SettingsLoader: Writing settings to disk. MewnBase: SettingsLoader: validating settings file MewnBase: Compiling shaders... java(92750,0x7fff9a00f380) malloc: *** error for object 0x12db1b1a0: pointer being freed was not allocated *** set a breakpoint in malloc_error_break to debug [1] 92750 abort java -XstartOnFirstThread -jar MewnBase.jar