Free games to beat away the slow season and, Beat the summer heat

I am broke, 
Far beyond broke. I also, have been playing a fair amount of oddities this summer. With that in mind I thought I'd put together a list of some of free games you could be playing.  


system shock  
n (the first game not N+ but, still a ninja game)

super mario bros crossover


cave story   
frozen bubble
Thanks to the GiantBomb user

louiedog I realized a grave error in not including Octodad and, 

Please if you enjoy it kick in a few bucks so part 2 can get made.

Collections of games,

Digipen is filled with student projects. I couldn't tell you what is good or not in that but, There are a ton of little games. 
Reloaded and abandonia are filled with abandon ware and free ware games. Even though sometimes abandonia has a buy through link instead of a download link and,  both sites have games that can sometimes be a pain in the ass to get working with modern computers. 

not exactly “free” but, close enough,  
I also forgot, you can get Back to the future episode 1 for free on telltales site
and, Wolfenstein: Enemy territory
there are also a few things on steam for free provided you want to have a steam account like Team fortress 2 and Trackmania.
I say free but, not free because you have to register them to use them but not a bad deal for a free game.   
Hope this list helps someone play something they will enjoy.
I will add a secondary note in here that if you enjoy any of the above games or any game for that matter please support those games in whatever way you see fit. 
Be that by money or simply sitting down and, Writing your favorite game makes a note. Working in the video game industry sometimes can blow. It's cool 
to know people like what you put your heart into.