This is easiest way to make screenshoots of your game.

[cairnswm]

Hate to be a smartass here, but

Does anyone know that if you press Alt-PrtScn
You only get a picture of the current foreground window, instead of the whole screen?

But this puts it in a file. Also excludes the Title bar and frame if a windowed app

So while running the game you can make multiple game shots