1.) A slider + jumper could be subsituted by a glider in a lot of design cases. Updrafts can also help to correct the trajectory.
2.) The turnaround of a slider can be substituted with a walker. In the case of 2 horizontal platforms parallel to each other a glider + cloner does the trick.
3.) If you want to simply get down: Floater/glider/updraft + maybe a walker/cloner
4.) Interruption of a climber. We have the jumper option now. You can design keeping the arc in mind.
5.) Jumper -> sliider: Jumper + floater should achieve similar things.
Puzzle potential is not only so much in things a skill can do, but often even more so in the things it explicitly can't do. Just like with the permanent-skill-removal object, people seem to start out by thinking about the new upsides a skill has, and how frequently those would come up - rather than about the drawbacks and how you can build around those.
Of course a Floater can get you down easily - in fact, often
too easily. In the past people have repeatedly pointed out how they were having trouble implementing the Floater into puzzles in clever ways, because it's just so limited in what it does. Let's pretend the Floater didn't exist in NeoLemmix (and had never existed in the first place), i.e. it would have to prove its value standing completely on its own ground - would we bother adding it? A skill that basically does nothing else but "survive splat-height drops"?
The Slider can only go down in specific places. Finding those places or creating them in the first place can be an interesting part of a puzzle. The most challenging puzzles are often about how to accomplish a thing that's pretty commonplace by itself: Containing the crowd, isolating a worker lemming, surviving a drop, or simply turning a lemming around just the right number of times.
And this is the other big selling point of the Slider: His distinctive way of turning lemmings around.Since he usually looks the other way than all remaining Fallers - and does so by default, rather than requiring a Walker / Cloner assignment every time, as it is the case in your examples - he can be useful to isolate a worker lemming from a non-contained crowd.
This way, he can be a powerful tool for very challenging flow-control puzzles. But rather than the Walker, which is often regarded as overpowered, you can't simply turn him around anywhere - you need to use the terrain to your advantage, find a drop where you can turn the Slider around, and only there it will work.
Other times, the fact that he turns around will backfire, just like the fact that the Climber goes over every straight wall. That is also usually an advantage, but it can be a disadvantage at times (again, one of the main points raised in favour of the permanent-skill-removal object).
I know some people regard the Slider in its core applications as nothing but a "weaker Floater". And usually, this raises the question: "Why would we want something that's just a weaker version of an existing skill?"
But I think I've sufficiently shown how this is not such a clear-cut case as Swimmer vs. Kayaker (the Kayaker is strictly worse than the Swimmer, because it's single-use, and there is no situation in which drowning is better than being a Swimmer - unless you explicitly need to kill a lemming to prevent it from doing some kind of damage, but by that logic, any "bad" skill good be good
).
Rather, Slider vs. Floater is like Stacker vs. Stoner,
Platformer vs. Builder: A huge part about the NeoLemmix Platformer is that it never gains height, no matter how hard you try. This is of course an advantage when it's applied to the type of level it was designed for - building under low ceilings without the lemming bumping his head.
But more often than not, it is used in levels that only provide Platformers, no Builders, but still require you to gain height some other way. In those levels, the Platformer is clearly disadvantageous compared to the Builder - but that is precisely what creates the challenge! For example, your point 5) only holds up when the lemming needs to jump across a gap in order to be able to float down safely. If there is terrain connecting the position where the lemming drops and where he's supposed to land, he can simply float down directly and walk, no jump required.
However, if you don't have a Floater, only a rough cliff under which there is terrain at splat height, the Slider will not be able to get down there directly. But let's say on the other side of that cliff is a straight wall. The lemming can now jump over to the other side and start sliding from there. It's basically like "one-way arrows for splat heights"
.
A Glider obviously can solve both scenarios on its own. But that is precisely the reason why a Glider is often too powerful for such level scenarios - at least on higher ranks. Just like Builders can be too powerful in levels that are about height-gaining (--> challenging levels will provide only Platformers instead), and Platformers can be too powerful and levels that require construction under low ceilings (--> challenging levels will provide Builders instead).
To convince you more in terms of puzzle potential here are some examples for both skills that I just know thought of without much thinking around:
- Stoners/stackers to create wider platforms or removing them.
- Destructive skills with make a path for the projectile to fly through.
- Create platforms for lemmings to fall on. (Thrower)
- Create holes in walls for something like a glider. (Mortar/bazooka)
- Create terrain to shimmy under it. (Thrower)
- Remove terrain to allow a climber/shimmier/jumper to continue. (Mortar/bazooka)
- Cloners give the ability to hit the left and right side.
This list, although it includes some nice ideas, is somewhat "dishonest" or at least misleading, because you put both distant destruction and distant creation into one list, either assuming that we will have both eventually, or depicting the puzzle potential of the individual skill (meaning only either distant destruction or creation) as more vast than it actually is.
Apart from that, I just want to say: Creating terrain with the Spear Thrower to shimmy under it sounds very precise . Especially since one spear is probably not going to be very long, so you'll need to stick several spears into each other back-to-back. And the Shimmier is very sensitive to height differences - any deviation of two or more pixels between two spears would make him quit. Thus, I can only see this work if the Spear Thrower always throws at a straight horizontal line. That would basically make him a Platformer with range.
Except that the spear would be thrown over the lemming's shoulder, i.e. it would not land at the height of his feet. So he couldn't actually walk onto a path created by his own spears.