If this were UT3, the slime would be okay, but in TF2, it doesn't seem thematically consistent, it conflicts with the pre-existing color palette of the game, and it just isn't fun. I very highly recommend you either replace the slime with normal water or don't have it at all.
Personally, I don't think you should get rid of the slime completely.
Just tone it down a little; make it only block off really useful routes or out of bound areas where players shouldn't be heading anyway. And please get that color changed.
I'm way too stubborn to give up the toxic sludge gimmick. While it's maybe the one thing that completly destroys the map, i still feel it's whats makes it special. I do agree though, that right now it's not working the way I intended.
For the next version I'm going to halve the damage from the sludge, instead of adding medium healthpacks at the end of the sludge routes (to prevent people from swarming the healthpack and thereby making the route useless as an flanking route). Also, the sludge is getting a nobuild, or for teleporters at least. I don't want to limit players too much. I didn't nobuild it completly originally, since I was interested to see if engineers would hide their teleporters under the sludge behind enemy lines, which wasn't the case at all.
i don't understand the point of the slime at all. you give a player the choice of guaranteed hurt vs maybe an enemy will kill them and they'll take the chance of an enemy every time. I'd rather it just be deathpit tbh.
I was going for some risk/reward thing with the slime. You have to really have an overview over whats happening, and where the enemy is. If you don't, they can force you to stay in the waste, where you're already weakened, which means every class is a threat. However, if you make it hrough, you are being rewarded with a strong position/skipping a chokepoint and a quick healthpack to make of for your health loss. Since the slime hurts over time, you are being forced to keep moving, and make fast decisions. It also makes it more risky to ninjacap, since you're pretty weak when you finally reach the capture point.
The sludge also allows me to have a wide open area, without having it being dominated by snipers. Also it allows soldiers to "super rocketjump" and land from high areas without taking any fall damage.
Also, in retrospect, this is maybe the dumbest crap i've ever written, since the height disadvantage and no cover already is one heck of a risk. Whatever.
I hate to sound so negative. I feel like I'm coming down really hard on your map because of just one single problem, but the truth is that your map was super fun and excellently balanced, and it looked great (again, except for the slime). Please don't be discouraged by what I've said, because I loved your map, and I really want to see it reach completion.
By the way, do you plan on making this 3-stage? What you've made so far feels like its just the first stage of a Dustbowl-style map.
Don't worry about sounding negative. Harsh feedback strengthens the character. And I prefer it over sugar coating any day.
It actually has a uncompleted first stage hidden away in a vis-group, an I have been planning on adding additional stages later, when I have resolved this entire slime issue. I used to have some sketches from the 72 hour contest, but I believe I have trashed them. They were even worse.