I found the tooltip in
9 slightly cryptic. It took me a while to figure out the first trick, as we briefly discussed in the discord. But after that, it
still took a while after that because there is multiple promising 'tricks' in the bottom left and I ended up picking all of the wrong ones first. You can have a walker step up onto the stacker mid-build in the bottom left, then turn them into a shimmier to have them shimmy up toward the top by themselves for example, which I thought was the intended path for a while. My fault.
For
10, the hard part was the bottom right. I spent a significant amount of time (~30 min) trying different combinations of stackers/builders/platformers, but the closest I got was one pixel short. You can see where I got here:
https://media.discordapp.net/attachments/249720184116477956/938209876763607090/SPOILER_unknown.png Eventually I gave up and asked for help and was given the solution to it, so... technically I never actually successfully solved this by myself.
For
13, I think the puzzle is really good but also really tough due to how much is going on at once. The whole block of 8 through 13 is, imo, harder than 14 through 16, so I think those two groups of levels should be swapped around. One thing that really caught me off guard is that in the bottom right, the timing works out perfectly (at least in my solution) if the first lemming that arrives becomes the stoner, then the second lemming becomes the builder worker. My first instinct was actually the opposite... I used a slider to make the first lemming that arrived the builder worker, then the second became the stoner... but if you do this thinking it'll buy the worker my time, it actually ends up not working out. A little bizarre, but hey.
For
20 and
27 I have no complaints, they're just tricky, but in a satisfying way. I know 20 in particular has been a real pain in the butt with regards to backroutes, so hopefully this solution is the actual one at last, because it's really cool!
For 20 the main thing which took me a long time to realize was how to get the crowd up to the exit despite not having any construction skills at that point. The fact you had to let the crowd past then trap them on top of the ramp using the blocker was the ingenious trick I was missing but did eventually realize. Very clever. For 27, the hard part was figuring out a way to release the crowd
after fully preparing the path ahead. I eventually realized I could do it by assigning the lower miner ahead of time and then releasing the crowd later using a climber-bomber.