I just finished playing the game last night and thought I'd leave a comment. It sometimes would freeze when fixing a leak, but the game itself was smooth otherwise.
While rough, I did like the choice to combine background stills from the original short with the newer drawn characters. I don't know if it was intentional or not, but it made me feel something was "off". A kind of atmosphere that you recognize but can't help but shake off the feeling that something is wrong. When combined with the night time levels, this really excels at making you feel the suffocating darkness of the ship. Even the area with the 3D effect was done well enough that I could believe it was connected to its source material.
SPOILERS BELOW
The missions, while basic, helped kind of break up the monotony of searching around the ship for holes, and I do think the passengers all had their own little personalities shown in full. I enjoy that some people do comment about how unnaturally chipper Mike looks, with even the Cleaning Maid's dialogue about noticing that Mick is acting off was a nice touch.
If I did have to nitpick, I'm not really sure what the point of whatever kills Mick in the tutorial is. Is it a parasite or a monster that takes over his body? Does it have any significance to the other monsters on board? That being said, you did address it in an earlier comment before.
My understanding of the story is that the briefcase the trombone player (they're evil, just like in real life) asked Mike to smash is the cause of the monsters on board and would have to be present during the tutorial, and as the day progresses, more people are either mutated or killed off. All until it's just "Mike" trying to keep the boat afloat until he escapes.
(or maybe the lore were the repairs we made along the way)
Second, the music can get repetitive since it's a sort of static ambience that doesn't vary or alter. It helped especially during the night portion of the game, but during the earlier segments, it's a little grating when you're running to fix leaks or talk to passengers for 5 levels in and you still hear that eerie noise.
Overall, I enjoyed my time playing it and I think it's a pretty good short experience! You did an amazing job here and I think this is a better Steamboat Willie horror game than the others that we've gotten since it hit public domain. For not having a clear vision of what you wanted to do, I think it's still a fun game for what it is and would love to see the ideas expanded upon if you ever did want to return to it.