How to enable OpenGL 2.0 support on a Windows guest on VirtualBox

I am trying to run some games on Steam (specifically Dota 2 Rebo) on a Windows 7 64 bit guest under VirtualBox ruing on a Fedora Linux 23 64 bit host. I have enabled 2D and 3D acceleration on the machine settings and I have installed the guest additions with support for Direct 3D (I unchecked the "stable", basic version). But the game still won't run and complain about not having support for the minimun requirements:

Missing basic OpenGL v1.0 -> v2.0 required OpenGL functionality.

My VM's settings are:

• 4 cores assigned
• 4096 MB RAM
• 256 MB video memory
• 3D acceleration enabled
• 2D acceleration enabled

How can I run this game with OpenGL support?