Need to kill some time? On a coffee break? Eo Minis are what you need. These games are not as fully fledged as their big brothers, but are intended to be small and fun to play. But what they lack in size, certainly does not mean they lack in quality.
You will also find games here that are the result of programming competitions held at the community often. The competitions (or challenges as they are known here) are done to help members focus their efforts in a particular area of game design. They also feature restrictions such as only using 4 sprites in the entire game, or perhaps base the gameplay around one aspect. This also helps focus skills.