Thank you Aram for pointing me on Powergame Factors. It is basically a software for Mac OS X which allows people to make their own side-scrolling shooters by plugging in their own artwork, using a level editor, and controlling some variables. In the same vein as the DIY MMORPG.

Power Game Factory is a satisfyingly complete side scrolling action game development tool. Here we'll introduce you to each major component of Power Game Factory and explain what can be done within each of the program's various windows. There's a lot of ground to cover, but you'll gain a solid understanding of Power Game Factory with no trouble. For example, making characters is easy once you've learned how to design projectiles; both are created using similar sets of animation and sound editing controls

Why do I blog this? because it's a great example of giving power back to the users! Besides, I heard that the next Nintendo console will allow amateurs to author their own games (anyone would then be allowed to run his/her own code. That's a good move: give power back to the user and then the pro-am debate will be more and more relevant!