This is probably my favorite custom region so far because it seems to be the only one that has an actually unique gimmick. Other regions all feel like a rehash of existing mechanics or a remix of an existing region. I love the concept of platforming above pools of acid, and the new acid hopping salamander does a great job at playing into this gimmick. You have to turn invisible while platforming, otherwise the lizard can spit at you and knock you into the acids below.

However, I still have criticisms for this region that I hope will see improvement. Firstly, it's too simple. Looking at the map, it looks like two horizontal stretches of rooms with a tower in the middle. Even topographically, I don't think any of the existing regions in The Watcher are this basic. Plus, all the rooms are a bit repetitive and look like they mostly repeat. Rusted Wrecks is an example of stuff being in a straight line, maybe you could look to that for inspiration on how to make everything more varied. Secondly, there isn't as much emphasis on platforming as I would like. Every room feels like you're jumping from one pole to another, and that's the whole gimmick of every room. You basically jump a pit, go to the next room, and jump another pit. I think you could take a lot of inspiration from Verdant Waterways. I am imagining a large open room with multiple screens and a pit of acid at the bottom, having to platform between poles and solid ground and avoiding acid salamanders and blue lizards. This kind of room would be very difficult for any other slugcat to navigate, since you have to rely on invisibility to avoid predators. Lastly, I wish this region felt more cohesive in terms of what purpose this facility serves and how it all relates. Right now, it feels like a bunch of rooms connected together without much purpose.

Here is my proposal for solving these shortcomings:
This overhauled version of Corrosive Geysers would be a slag filtration system for an Iterator. On the right, you would have Iterator-like architecture full of acid pools. The geysers that spew acid are venting slag from the Iterator to circulate its systems. This area would be mostly full of acid salamders, and maybe some blue lizards since they can climb on the walls and avoid the acid. Blue fruit or slime mold could be present here to provide a food source, since that's something currently lacking. In the middle of the region, the tight tunnels open up into a huge vertical shaft similar to that seen in Verdant Waterways. This huge shaft would be a large ballast tank where the toxic slag is processed to turn it into harmless water. The acid levels in this room would fluctuate rapidly as slag fills the tank and then is drained. I'm not sure if you can make it so the acid turns into water when this happens, but it would be an amazing visual effect that perfectly demonstrates what it's doing. To the left of this, you would have pipes of water constantly pumping large currents through the underwater rooms, and would resemble Turbulent Pump, but to a lesser extent. After a few rooms of current-filled waters, you would enter the more calm waters full of normal aquatic threats like salamanders, tardigrades, barnacles, bubble fruit, etc. At the end of this hall, you'd exit the canal and into the ocean. In the upper half of the region, you could show what happens to the chemical byproducts separated from the water. Rooms full of a thick sludge and waste building up on all the walls. These areas could see the return of the Basilisk Lizard from Fetid Glen, who thrives in the dark halls full of sludge and scum. This area would also have prey animals that feed off the toxic byproduct, like lantern mice, bat flies, and tardigrades.

Thank you for listening to my seminar. Help yourself to some complimentary mints on the way out.