The Climber stops climbing, yes, but it doesn't "lose" the Climber skill in the sense that it doesn't suddenly fall off the wall.

Instead, with the Climber remaining in its place when oh-noing and sort-of "standing in the air" while doing it, one could argue that Swimmers should do the same, i.e. "stand" on top of the water area an finish the oh-no-animation plus the explosion, rather than continuing to fall.

Floaters and Gliders can't oh-no, and coincidentally, Oh-Noers can neither float nor glide, because they never reach splat height anyway before exploding, as I've repeatedly outlined in this thread. So we never actually see whether they "lose" the skill, unless you'd want to argue that floating or gliding lemmings already open up their parachutes very early during a drop, i.e. even before a regular lemming would reach splat height - and Oh-Noers don't.

If the Lemming should not behave like a swimmer that therefore renders out swimming (after the basic assumption) and exploding (as that would imply that he switch to swimming), he should behave like every other Oh-Noing and simply drown, what would be consistant with 1.) on top of that: A oh-noing swimmer should not swim anymore, but again should be "eaten" by the water.

Now, try assigning a swimmer to the ohno'er before they hit the water (you can't do this during the ohno, it must be done before assigning the bomber). Notice how instead of drowning (since swimmers can't drown), they continue falling to the bottom of the water, exploding when appropriate. This part, IMO, is fine.

Two levels (2 and 11) I can't play though, because of a missing "flame_deco" piece in the Marble tileset?

Spoiler (click to show/hide)

Since you put stoners and stackers into one level, I'd really find it helpful if you could somehow enforce or at least mention the trick that a stacker can be used to get over a stoner by closing the gap at its feet (in fact, I also have a "stacks and stones" level that uses precisely that trick! ). Usually people only perceive both stackers and stoners as blocker-surrogates, especially when they're introduced together and when it comes to getting over them, they will therefore resort to building or platforming from a ramp. The stacker-stoner trick effectively makes use of the six-pixel-jump, because the stoner's shoulder height is six pixels. If you think this is too much for this first level on the two skills, which I'd totally understand, I suggest dedicating a separate level in a higher rank to this. Six-pixel jumps are also relevant to stackers in combinations with walkers, after all, when the player cancels the stacker prematurely. Since walkers don't fit into this level, I guess a separate level on six-pixel jumps, featuring stackers, stoners, and walkers might be the best option.

In the climber-shimmier level, you call both of them permanent skills. Shimmiers aren't permanent skills, though .

I'm just in the middle of downloading all the styles for 12.6.1. It's too loooong. I wonder if it's possible to reduce the size and thus, the length of the download. One possibility maybe is to only include the official graphic sets, and put all the custom ones in a separate thread.