Hey, first I'd like to thank you for your site. It's helped me recover a lot of great maps that I lost when my hdd failed and I couldn't find these maps anywhere else but here.
However there is one UMS defense game I used to play (Muffin Defense or Defend the Muffin something like that). I only saw it hosted a few times on BNet so it's definitely not a popular game.
Anyway there are six players I think they are set horizontally across the bottom of the map, with each player getting their own box to defend. Monsters come from the top and bottom of the box and the left and right sides of the boxes on the far left and far right. The leaks would go to another area at the top of the map above the players' horizontally set boxes. The leaks would start all the way to the left and then run to the the right in a straight line, and at the very end of that lane would be the muffin, which had to be defended. Players could also defend the lane and kill the leaks before they reached the muffin (which had only 10 lives). A couple of levels or so there'd also be a set of monsters that ran from the top towards the muffin before starting at the players' boxes. Players also could buy different units like in most defense maps and buy minerals to upgrade them.
That's the best I can describe it I'm sure "Muffin" is in the map file name. I'm not sure if it's a scx or scm map though. Also it could be misnamed somewhere so if you ever come across a map like this, hey it would be great if you could add it to your collection.
I don't have any "Muffin Defense" in my collection and couldn't find it on the Internet either I guess its obscurity secured its expiration. By the way, telling me the tileset would help a lot (and it's also easier to remember) rather than telling whether it's scm or scx.
Anyway, what made the map so great that you're here to request it? There are thousands of defense maps, hopefully you'll find one that you'd like as much as "Muffin".