Cookie Clicker (
http://orteil.dashnet.org/cookieclicker/)
aka
Know Your OCD Level
(First up, I have to admit that I have not completed this game. I am not sure if it is even completable, but I am going to find out.)
You start out as a normal lad/lass that feels like baking some cookies. You click the giant cookie on the left of the screen until you have enough cookies to buy a "cursor". Cursors auto-click every second to help you produce more Cookies. Now it is you and the auto-clicks generating cookies. Soon you can afford another cursor and another and another (prices increase by a few cookies each time you buy something to make it a bit more challenging). Soon, just having cursors are not enough. There is a giant market for cookies out there that needs to be satisfied and you need help. Recruit a Grandma.
As things stand at time of writing, there are 9 different cookie producing buildings/devices/people that you can purchase. Add to this 86 upgrades, 77 achievements, occult research, milk levels and golden cookies, and Cookie Clicker will feed your OCD for days, if not weeks.
At its heart, Cookie Clicker is a very simplistic management game with little in the way of strategy required. The story (yes there is one, if you follow the news headlines) is vague and systematically turns creepy as you progress and the army of Grandmas turn restless.
Rating:
2/10 for challenge level.
8/10 for addiction level.
You'll love it or hate it. No middle ground.