Surprising small games
Some flash games can become really addictive while being utterly stupid. For instance, clickclickclick offers an internatinal contest of clickers. There is a rank table showing how much clicking has been done by each country. If you want to be patriotic, you’ve got to click frenetically on a big red box. The gameplay is simplistic yet addictive, at least for 5 minutes.
Boxhead 2 on the other hand, is a nice zombie survivor game. It introduces a shoot counter giving you updrades when you’re in your best killing spree. The variety of upgrades and the big number of enemies renew the gameplay at each level, making you play for hours.