... I was amazed at the weekend when my GF was out, she showed a couple of her dads friends my crappy little rock game and they sat and played it and enjoyed it lol.
I had a go of the rock game, played it a while over lunch, its very good and easy to lose track of time. If you look at something like Temple Run, they took a simple idea and put in the upgrades and suddenly you have a reason to do the same thing over and over.
I used to play WoW and Star Wars Galaxies, any game where you can level up and get new stuff.. I can get addicted.