The Spyro article goes into loads of details of extra checking and ways to make it harder. One of the best ones they added IMHO was having it appear to play normally, but only 2+ hours into the game it would fail to give you a quest-critical item if you were using a hacked version. Hackers usually don't actually play the games that much, so forcing them to play for a good period of time, and then making it look like they just missed something in a level is a good way of drawing the whole process out.
yeah that really a great way to do it - check for it, at a certain point
it's just like demo then
at that point I just show a video, in the game, of game developers being pushed, hungry and weak =D