I've created a simple 3 level platformer game complete with a boss at the end specifically so any game artist can easily (and completely) change out any of the art, sounds, music etc. to create their own platformer game. I made it using the free edition of Construct 2 from http://www.scirra.com, so you don't need to buy anything to use it and the finished game can be exported as HTML5, which means you can embed your finished game into any website including your online portfolio.
I've also begun creating tutorial videos explaining how to replace the art and will soon even make videos explaining how to “program” in other game play features. (see the link above)
You can also try out the actual game here: http://www.brashmonkey.com/skin_platformer/
(For people like me who love pixel pushing, fear not, I'll show you how to make the game run in non-scaled, not filtered, pixel perfect mode.)
To play, just use the arrow keys to walk and jump and the Z key to throw fireballs once you've collected the “power-bean” .
And for those interested in seeing how far you can take this engine with the full version of Construct2 (the free Construct 2 has a 100 event limit..the current basic engine uses 91 events), please check out this really robust game thats being build on top of the same engine:
Backers of just 55 dollars or more can get the entire fully featured game engine once the game is finished.
I hope people find this useful.