Minecraft N00BS go on hilarious adventures.
Blood, bullets and Hot Cheetos... Just another day in Necropolis.
The ultimate stick figure series, and a bunch of goofy parodies as well!
While a majority of web games from 1998-2009 were made with the Adobe Flash IDE, the SWF format has since become open and a variety of frameworks and tools have emerged (many of them free) to facilitate game development! If you're interested in any of these platforms, here is a place to sample games made with each one.