How to make a game full screen on my external monitor?

Solution 1:

Using google i came upon this page: Full screen app mode doesn't play wel with external displays.

Now this is only with fullscreen apps but I think it might be the same problem. Reading a bit futher in the comments i found this :

Just go into System Preferences > Displays > Arrangement and move the white menu bar strip to the external monitor’s rectangle. Full screen apps seem to associated only with whatever is considered the primary display.

Ps: Don't have osx so I wouldn't know if this works...

Solution 2:

You might be able to do it using F7 or FN+F7:

I believe that the standard F7 key is to change display modes when hooked up to an external monitor or projector.

It should look like this with a helpful ambiguous icon:

Solution 3:

I'm running OS 10.9.3 using a MacBook Pro 17" with retina display connected to a 27" Studio (Thunderbolt) Display. I mirrored the displays, then selected optimize for Thunderbolt Display. When I want to use both screens, I just deselect Mirror Displays, and it switches right over. It's the only decent way I've found to play games or watch movies/TV on my Studio Monitor, but it works fine!