Please obtain the following jar files to place them in lib/ : jbullet.jar vecmath.jar lwjgl.jar lwjgl-glfw.jar lwjgl-glfw-javadoc.jar lwjgl-glfw-natives-windows.jar lwjgl-javadoc.jar lwjgl-jemalloc.jar lwjgl-jemalloc-javadoc.jar lwjgl-jemalloc-natives-windows.jar lwjgl-natives-windows.jar lwjgl-openal.jar lwjgl-openal-javadoc.jar lwjgl-openal-natives-windows.jar lwjgl-opengl.jar lwjgl-opengl-javadoc.jar lwjgl-opengl-natives-windows.jar lwjgl-stb.jar lwjgl-stb-javadoc.jar lwjgl-stb-natives-windows.jar
Afterwards this project should open nicely in eclipse.