I've definitely done some looking into this game as far as trying to route a speedrun (not a lot, I've only looked at the beginning/starter island). I haven't found anything particularly interesting as far as big skips or anything like that. From what little I've done this game seems pretty linear and hard to break open to go really fast. I'd love to trade ideas with some folks on here though to try and figure some stuff out. I've seen what runners are capable of with games long thought unbreakable. If anyone wants to bounce ideas around I'd love to be a part of it.

Sorry was a bit late to seeing this post. I have done some runs, just haven't submitted anything yet. Yeah the game forces you to be very linear due to text not appearing if you skip things. You can actually get to the blimp right away, but as of now haven't found a way to progress the story. Haven't tried all options to see what lets you do things early, but so far the list of things I've tried that haven't worked:

Doing Crypt before Cave (you can finish it, but you need to go back through the Crypt again after completing cave to talk to the King's son). Going to volcano early (text to give you the key to enter isn't available) Talking to king early (text to open blimp doesn't appear, not that it matters since you can get blimp early without gate opening)

Still need to test if you can complete anything in the desert early and perhaps use the better items to complete island 1 faster and have all the progress you made in the desert still count, and obviously see if that would be worth it time wise.

Is there a guide to learn the game?

Guessing you are the same person who I let know on Twitch, but verified my old run for an example as I do not have a written guide. The run was probably my second attempt so definitely there can be improvements. Not a lot of usable sequence breaks in the game as dialogue options do not appear to progress if things are done out of order, despite you being able to get to king and even the blimp at start of game. There may be more same island sequence breaks that haven't been explored yet however.