Stable Version and Common Bug Fixes
For any new users, if there are unexpected errors when using the latest development version, try using the stable version. The newest versions won't run on older graphical hardware due to the features that aren't supported on it. More details can be read on Jason's blog:
Also, I'd like to start a list of common bug fixes here that new users can scroll through - sort of an FAQ. Feel free to add responses and myself or another admin can edit the original post to contain a list of fixes.
When I try to run Env3d, the window freezes and I get a message saying "java.lang.UnsupportedOperationException: GLSL and OpenGL2 is required for the LWJGL renderer".
This means that you're running on older hardware that doesn't support the rendering/shading features from the Java Monkey Engine that are a part of the most recent development versions. Try using the latest stable version.