Yes, it truly is Le Editeure du mappe! Excuse my horribly broken French, but I am in fact referring to the map editor for my contest entry, Admiral Overalls.
So far the map editor is basically the modified game's source, with a bigger resolution, scrollable via the arrow keys, and able to edit the map with the mouse buttons (left for place tile/sprite, right for delete tile/sprite). It's so easy it should be illegal. It very likely is.
As you can see the interface is quite simple. Since time is the major constraint, as with any contest, the KISS method (Keep It Simple, Stupid!) was deemed the most appropriate. We have the left SDL-rendered window that draws the map and its tiles/sprites -- sprites being entities like enemies, powerups, and their ilk -- while the window on the right lets the user choose their palette (tile or sprite) and choose whichever they please.
Currently placing tiles/sprites is pretty simplistic: point and click. This gets to be a royal pain when needing to fill in solid areas, like the large region of 'dirt' at the top-left area of the screenshot, so I'll probably end up implementing a rectangle-fill feature sometime in the near future to avoid future pain. ;)
Draffurd has drawn a few really cool enemies that are both comedic and will make for some interesting gameplay. I won't unveil anything, except that one of them is inside a cardboard box. Literally. Don't worry, you'll get it when you play. :P