virtualbox.org

Just FYI, safe mode is required if you want to install the older Direct3D graphics driver. The newer WDDM one can be installed in normal mode.

Gaming in a Virtual box is a bad idea. You wont have the great 3D support that you desire and applications that require a lot of resources will lag. Some games will probably work, like minecraft and minesweeper. But running heavy programs like Battlefield, Skyrim and similar will not work.

The reason for this is that you are basically running two operating systems within each other and the one you will be emulating will be limited to a small portion of that computers resources.

A solution to this problem is dual boot. For example you have one partition with Linux (where you are all serious and stuff) and one partition with windows (for gaming). I had this setup on my laptop for several years it works great.

There are instructions in the Ubuntu installer for how you install with a dual boot setup. The easiest is to install Windows first and then install Ubuntu.

You can also try enabling 3D Acceleration in the guest settings and installed Guest Additions after doing so? I think it has to install a special driver once that setting is enabled. Right click the Virtual Machine >> Click Settings >> Select Display
Now tick 'Enable 3D Acceleration'

Good luck.

I'm also trying to run CS:GO in a VM and so far I haven't been able to.

I tried installing both the "experimental" 3D support (from Guest Additions) and the "basic" one (by booting into safe mode). Neither of them works, I get an error related to "engine.dll_unloaded" from csgo.exe.
The guest OS is Windows 7.

I have the same error. Which driver did you install?