Oooo this... I like this.
The look of the ship, the spooky tunes, the eerie creaks and crashing waves. Definitely top marks for Sensory. I don't know if Spirit Farer was an inspiration on the visuals but it kinda put me in mind of it.
The time swapping worked well and intuitively for the most part. I struggled a lot at the first puzzle, not realizing that being too close to the ceiling was preventing me from swapping mid-air.
And there's a slight inelegance regarding the lack of visibility, especially with two worlds to be concerned about. But given the rooms aren't too large, and you get a check-point on entry, it allowed for plenty of trial and error.
Perhaps in a full game, showing the outline or ghost of the other world when you try to swap and there's an obstruction would help.
Really liked the feeling of mystery. I would have live to have seen what you could have done with the story given more time, and the insights there might have been into the soul-bound items. Maybe a Soulsborne style item-description based unravelling.
I do have an interesting bug to report. (Perhaps completely superfluous actually.) I was recording my playthrough, and accidentally cut off the ending. Figuring I could just start from the beginning and speed run to the last section, I restarted the game. But after getting two abilities, I didn't get my new moves.
I figured whatever was making the unlock ping wasn't triggered because the game already though I should have them from my previous playthrough. Not sure where the save data was exactly, I deleted and re-unzipped the game. That seemed to work, so I think I was right.
Anyways. I'll post the footage once it's up.
EDIT: MM21 - Tides of Time
EDIT: Oh, and it didn't effect me because I'm playing on a big screen, but the text on the starting letter might be a bit small. And there's a repeated phrase (Captain, stubborn but cool or something). Couldn't tell if it was repeated for dramatic effect or not.