TicTacWin

Bigger bug: your logic is incorrect here - you can win - try bottom left, top right, bottom right, bottom middle - that looks like a win to me! There IS a way to make sure that the human can't win, but you have to be cleverer than just looping through all the possible things that can happen for that move, you have to stop the game getting into a situation where a win is inevitable (which is what happens in the above example.)

If you get really stuck, you can have a look here at something I did a while back - http://mikkle.co.uk/content/naughts-and-crosses - it's a netbeans project that uses Swing rather than Greenfoot and the coding isn't the neatest, but the logic's all there and it (I think) works as it should - so you can't win that is ;)