Ye I really doubt you can solve every grid with only 1 square up.

I've been looking into the game of lights out, it's simular yet so different. This looks much more complicated.

I understand that pressing a square any even number of times will have the same result as not pressing it at all. So it's indeed a matter of finding which to press and which not to press.

Each lighted up square much have an odd number of squares used around it.

Each pressed down square must have an even number of squares used around it.

My theory is that it's the easiest to solve when trying to bring the lit up squares all towards an edge or corner, 'clearing' the rest of teh area. But thats easier said than done.

I appreciate all the help you guys are giving. Would by nice to practise this game through a simple browser game like this:

http://www.logicgamesonline.com/lightsout/