What's the Mac equivalent for CTR+ALT+Backspace on Linux? I need to regularly shutdown brutally my Mac, due to program misbehavior (Starcraft 2 and EVE Online), which take control of the graphics and never surrender it back. 

While I admire the tenacity of those embattled programs... I'd rather nuke them with a single stroke, as I would on Linux by killing the X server.

The irritating part is, the underlying OS runs fine, since I can move the mouse around, change luminosity or sound. I just can't switch back to anything, work, email... so I have to fully reboot.

How do I do that? What's the secret key combo?
Command ⌘  + Option + Esc opens the "Force Quit Application" 
dialog, which lets you select and kill running applications. 

If that does not work, 

Command ⌘ + Option + Shift + Esc held down for 5 seconds kills the foremost application.