For me, the latest one to trick me into this pitfall is Plants vs. Zombies. Currently, I had owned the game for DS, iPhone, Xbox 360 and PS Vita. Well, today I discovered that it was only $.99 for the iPad, so guess what game I bought again, in all it's glory.
I have literally done everything there is to do in the game over and over again, yet I continue buy the game and play it over and over again, for no real reason at all. Other than it is a super fun game, of course.
For those living under a rock, this is a tower defense game, where you plant all different types of plants and flowers in order to stop the zombie hoard of each level from reaching the house. If they reach house, you lose. If you destroy all zombies, level over. Simple stuff indeed.
The charm lies within the characters of the game. Everything from the plants themselves, the zombies and even Crazy Dave, the characters and charm radiate from this game. I guess that's probably why I like playing it so much.
If Plants vs. Zombies 2 is anywhere near as good as this game, my wallet will be hurting severely.