I'm having trouble running Unity 3D in Ubuntu 12.04 LTS in VirtualBox.
I tried enabling 3D acceleration, it still does not show 3D. Only 2D.
I tried installing VBox Guest additions, won't show 3D.
The Ubuntu live CD session: no 3D.
The 3D in VBox is not enough to run Unity 3D.
Most Virtual Boxes have very poor support for 3D, at least the more advanced aspects like transparency and the like. I use VMWare Workstation and it has no issues. I never managed to get VBox's 3D working sufficiently to even run a simple game like Minecraft.