Avoid cats, pick up poo.
When I was a kid (10? 11?) I got a copy of HURG for the ZX Spectrum ( http://www.worldofspectrum.org/infoseek.cgi?regexp=HURG ). While I'd made little games and things in BASIC, HURG let me make "real games" - the sort of thing you could show your mates. I used this newfound power one day to make fun of another kid whose kitchen was always filled with cat crap. Oh, how we laughed.
Because I still feel bad about making a kid feel bad (sorry Darren!) I felt the best way to atone would be to make some other kids feel happy. So I asked my 6 year-old daughter and the neighbour kids (8 and 9 I think?) if they wanted to make a game. Their eyes lit up and graphics and sound effects and ideas spewed out of them, and their enthusiasm was only slightly dampened by my explanation that the game we'd be making would be simple. That it involved poo sealed the deal, and within a couple of hours we had everything ready to go. It's fairly similar to the original game I made, though I don't think I ever got around to adding the cats.