So, I haven't made a map for a GBA project in a whileeeee. Needed to get out of a creative funk and had an idea, so this sounded like a fun way to do so.
Below will be the map image and a ZIP containing said image, the TMX, and the tileset with altered palette. The tileset's palette should work in a ROM, but if there's an issue, let me know and I'll see what I can do - I was always more the graphics end of what I've worked on and less the implementation end. Ditto the previous in regards to the TMX - I followed the tutorial(s) so the tile change should work properly, but, again, implementation was never really my thing, so if it does break, give me a holler.
I started early, sue me. My days off were Friday and Saturday, so I figured I'd do this then when I was able.
The map is "called" 'The Cistern' - basically an underground water storage area below a castle in this case. Recently has been drained by someone be it a besieging foe or someone else, hence the bits of water left around on the floor (yes, they were intentional - if I could make my own tiles to make the loose water more appealing, I would have, but this is what you get). I wanted to keep the map open-ended enough that it wouldn't be strictly tailored to one specific objective - assuming I met my goal, it should be usable for attacking or defending objectives. According to the post in the Glitches thread, the dimensions on the map should be safe (28 wide by 45 tall) - again, if it breaks, lemme know.
The tileset is a palette swap of FE8's "1800191A" tileset using FE7's "0A00DC0C" tileset's palette as a base - it ends up with less colors than it started with (different palette banks sharing colors, I'm guessing?), but my graphics editor just flood fills unilaterally, so... The only tile change is the door in the top left corner. (You can use the default palette if you want, it'll just look more green-ish and kinda bland, IMO.)
I know 45 tiles tall might be a lot, but picture it as a near-endgame map or something - when I was looking for which tileset to use and came across the Ch 14x (FE6)/Athos Shrine (FE7) tileset+palette combo, something about it just had me picturing a fully rounded out Marth and co. being the ones that had drained the water, entering from the south, to siege the castle from below - an odd inspiration, I guess, but inspiration nonetheless. (Plus, with all of the real estate taken up by the wall heights, in order to have functioning passageways of more than 1 tile across the board, it needed to be tall...)
You may also notice what you think is a height error with the two little "overlooks" at the north; they are intentionally that height so, theoretically, if a unit with a long-range weapon was there, there wouldn't be a physical wall towering upwards in front of their face the entire way up to the ceiling.
EDIT - ...Forgot to de-tilespam a section. sigh
Too late, will fix tomorrow after work.
EDIT 9/5/17 - Fixed and links updated.