Been playing a fair bit of CTS the last few days, really having a blast! Good to see new levels, and I love how polished the wind is while still keeping to the "out of control" original guideline, being able to control your float with the orientation of the stick just blew my mind when I noticed it! (even though it plays a minor role in completing the levels)
I have quite a few recommendations, feel free to discard anything that doesn't seem doable or pertain to your vision for where you're taking the game!
Here goes:
Speedrun related:
1- A timer during play, seeing your pace as you go through a level can be very helpful!
1a- If you want to enable speedrunning for an "all levels" category rather than individual levels, another timer would be great to keep track of the total runtime, pausing when levels are completed and resuming when the next level starts.
I would suggest making this total timer feature dedicated and exclusive to a speedrun mode, rather than the initial "campaign" mode just because a timer could put pressure on casual players who just want to get through the game as a puzzle, with no pressure of time, only completing the level. (or maybe just make it hidden from normal mode)
2- A keybind to the restart option of the menu, to quickly be able to start over, this is pretty much just Quality of Life though
2a- Another option and keybind to start over from level 1, that'd also be a great QoL but only for a speedrun mode, casual players would NOT want to accidentally press a key and find their progress seemingly disappear. Keybind would need to be
2b- Ability to change keybinds ? That's also Quality of Life but that can be a massive boon to speedrunners
3- Making the end of level transition over a second or two into a menu that would have all previous options (except resume) but also a next level button, in speedrun mode it could just go straight to the next level one second after finishing the level, just so you have time to see your timer for said level. Minimizing menuing is always good when possible in speedrunning to keep the emphasis on gameplay, at least I think it is.
That's all I can think of for now relating to speedruns. This does NOT have to be your principal concern but keeping those kind of things in mind could be useful in the long run ? I don't want these things to take up your time and take away from your creative process whatsoever but wanted to adress what I could think of since you asked about it in the other topic!
Now for general additions, I think a handful of mechanics and levels introducing them are probably your first priority. Don't know that you need help figuring out mechanics seeing how good your wind is but do ask if you need ideas.
-Further down the line a map editor would be great for replay value/ community building, it could also help your own creation of maps if you do it early on, I think?
-Customization? It doesn't have to be a lot, but I was thinking of the game LUFTRAUSERS and it's color palette system, I think unlocking a level's color palette after completing it and being able to set it as default could be nice, or even as random! In case you don't know about that game &/or that particular feature I could make a quick video of it, if you're at all interested.
One last thing I do want to mention which is really quite subjective is what got me hooked in the first place, and that'd have the simplicity of controls, and the precision of inputs required to keep your controllable "stick" well, in control. I think mechanics need to be simple building blocks that add to the original gameplay, without changing it too much, and while the wind is great in many ways, I'm sort of afraid of it getting too chaotic, then again, not enough elements would not be engaging enough, so I guess you'll have to figure out the balance of chaos vs control. Either way I thought that was worth mentionning.
tl;dr : Timers! Menu options and keybinds! MAP EDITOR?!