I'm on a rather old laptop with a Radeon HD3450 and open source drivers (on Ubuntu 14.04). I get glitches when I launch the game, and it is unplayable when I join a game.
Is this because of the renderer using OpenGL 3? If so, what's the switch for OpenGL 2? (I forgot).
Update:
I've checked the wiki and found the arg to pass, but with or without, the game freezes.
This seems to be the cause:
"GL_ARB_get_program_binary found, but with no binary formats "