Hey, I just started a small escape attempt - to see how "really good" your map is ;-)
Judging by your profile-icon you're a big Quake fan (like me) ... and maybe you even played Wolfenstein/DooM ... because your map layout really feels a lot like those old games.
The reason I soon toggled into editmode to quickly scan the rest of your map, rather than follow it through to the finish was : it's too cramped.
Seriously - there's not even enough room to turn around (at least feels that way) .. definitely no strafing possible .. and quite a number of places where low ceiling keeps you from seeing your opponents (first slith opponent for example).
Apart from giving the player more of a challenge than just timing his shots to not impact on the (already disappearing quicker than they used to) hitbox of opening doors you should provide some space for moving about, trying to evade the monsters and their attacks ... giving one the impression of actually using some fighting skills ... and try to balance your ammo/health items to make life a little harder for players too - just enough to keep them alive and kicking (errh : shooting) .. but only if they play really well (try your map on different skill levels too! "/skill 10").
With the way monsters work in sauerbraten it is often best to place masses of them in medium sized areas - giving the player a mass-attack to fight through - at least once in a while ... not just one-at-a-time to be pistol-capped because at the right rate of fire you'll even frag a Bauul without him ever getting one rocket off!
You map file is indeed so small you couldn't do much more about it - but for your information:
If you fill all the inaccessible area with skybox-textured cubes this will optimize the octree - can be a big gain on larger/more complex maps!
Also:
It's absolutely sufficient to have 1 (one) monster outside the accessible area to make the map wait for the end-of-level-trigger, rather than for the last monster to be killed, before ending.
