My constraint here, adapted from the Ludum Dare #28 contest theme, is :

“ You get only one... pixel to make a game ”

It implies no intro screen, no explanations of the rules... you are all by yourself

need a zoom ?

Game A

need a zoom ?

Game B

need a zoom ?

Game C

need a zoom ?

Game D

zoom is broken :-(

Game E

Note : all games on this page are actually 1 px by 1 px canvas elements. Zoom is done with CSS and your graphic card.