Negative:
The background could look better
DON'T USE GENERIC_UNHOOKABLE (for hookable tiles)
The gfx could be better.
Something I don't like about the map is the huge filesize. You embedded the nrace tileset to use 2 single tiles of it, please use e.g. gimp to remove the rest of the tileset and embedd it again. The same for the text - tileset. This way you could save about 400kb.
You use the number 9 twice. I managed to get stuck at the bottom left of part 13, very annoying. The same for parts 18 and 19, and notice that the number of part 18 is missing. Parts 16 and 18 dont really fit to the other stages.
Positive: You said that the map needs 3 tees from the beginning on ^^
I found a nice control centre for admins.
Gameplay is good, most parts require cooperation, good usage of the doors.
The idea to give the players only 1 weapon at the end is nice, but I dont think this will keep players playing the map 4 times.
void ..