Yesterday I posted about a ping pong game that I had become addicted to and now I have a site with several different Flash games. You can find the list of games here and they are so simple that they are addicting. My favorite is Gravity which starts out pretty easy but it gets pretty hard.
One of the simplest game concepts would probably be Insanity. All you have to do is drop a ball in a hole and you get a point each time you drop it into the hole. I haven’t really found the point of this game because as the levels progress nothing really changes, but that is probably why this is called insanity. 
Note: You can find a game similar to Gravity here which also gets pretty challenging.
I spend most of my time playing Balldroppings
Not really a game but its funs for hours
[balldroppings.com]
That was very interesting and yet entertaining.
That KingPingPong is pretty tough.
You don’t want to know how long it took me to get a single point in the ping pong, but I am gradually getting better.
I’m learning the knack – I can get about 5-6 points. The key is to force him to make mistakes. Creep right up on the table and push the ball at him, don’t stay back and wait for him to make a mistake – he’ll crush you every time.
I’m not addicted. Really, I’m not.