IF you do in fact want to use your spacebar while playing,
you can right click on the "H" in the system icons, click on "Edit This Script"
- look for the only place in the code where it says "space::CoordMode"
and change "space" to "LShift" (left shift key) or "LCtrl" (left control), or whatever you would like to change it to on this key list:
http://www.autohotkey.com/docs/KeyList.htm
personally i do other things on my computer while im playing, although minimally.