Comment # 6 on bug 80584 from dex+fdobugzilla@dragonslave.de

I think this may be due to missing GL_ARB_tessellation_shader extension.

Mesa lists this as Status "started" but no driver implementation yet.

I'll try to evaluate the status of this and see if I can verify that its indeed
this missing extension.

(That would also mean that XCOM is in fact OpenGL)