If you want rules light RPGs, take a look at the 200 Word RPG Challenge.
The aim is for a playable game that grabs attention without being outside the bounds of the rules. One is forced to economize on words and get to the meet of the game. There are judges and prizes. The winner will have their game published.
Entries are in plain text and must be submitted via the form on the site. Contestants are advised to use the word count feature in Google Docs prior to submission. The title does not count towards the 200 word limit.
As an example, here is my submission, Cat Wrangling, also here.
Cat Wranglers earn experience gathering cats into their herd. Start with 2d6 cats and one method. Each turn there will be 1d6 new cats in your neighborhood, and 2d6 cats attempting to escape. Both ancient methods and new methods are used. Ancient methods include fresh fish, canned fish, caged canaries, and catnip. Cats may be strays, or those stuck in trees. Each method attracts 1d6 cats. New methods must be researched to maximize one's herd. Possible new methods are: cat yodeling, cat calling, breeding Andalusian catherd dogs, etc. Developing new methods are adjudicated by the judge with a difficulty level. Any creative and entertaining method is permitted. Enticements for cats to leave the herd must be negated. Threats include: big mama cat or old Tom on the prowl and frisky, mice on the periphery of the herd, song birds in the forest too near the ground, children with a laser pointer, stray dogs running wild, etc. The health of your heard must be maintained by cleaning the litter boxes and feeding the herd. Tick marks keep track of cats, food, and litter. Starting methods on index cards are assigned randomly. Each dozen cats attracts a helper and gains a level.