Hey hey! Thanks so much for playing the game :3 I'm glad you were enjoying it so far even if it wasn't functioning the way it was supposed to >.<
Unfortunately, I'm not even going to be able to look into this for you at the moment because the code for the version of the game you're currently playing no longer exists. So I'm sorry about that :( I don't know if you're aware of the big update I'm currently working on for DD, but yesterday I finished the complete revamp for all existing content.
Because I originally made what's currently available of the game as part of a jam, I only had 1 month to learn how to use Unity and Nani (cos I got it just before the jam, prior to that, I was using Tyranobuilder). As a result of the deadline + my inexperience with the new engine, my code was incredibly messy. Too messy to work with going forward now that I've learned a lot over the last couple of years. So I decided to rewrite all of it, along with making many tweaks and additions to the existing story content.
Once I release the big update, anyone wishing to continue playing will need to start over because I've changed so much that old saves and the old version of the game won't work.
Changes include: A brand new title screen with new original theme track, redesigned menus, a new introduction section where the player can pick their name + pronouns, a personality system, new backgrounds, more choices (including some timed ones), around 100 new lines of dialogue for Castor/ia (to account for responses to all the new choices), and various additions to Castor/ia's existing story content. Then there's also gonna be two more characters introduced + new story content for Castor/ia :3
If you wanted to check out my little progress updates, I post them on Twitter cos itch recommendeds only posting bigger updates here since it will send emails out to followers, and no one wants to be spammed x3
As you say, a small handful of people seemed to have that issue with backgrounds not loading, and I never managed to gather enough information to figure out why. They're only png files, so it's not like they're weird files or anything >.< But there was also an issue for some people where they couldn't get past the the title screen because instead of loading the video background, it loaded a black screen for them. I managed to fix that for people at the time by making an alternate version where the title screen just has a static png background rather than the video one, but I didn't want to have to keep releasing two versions with different title screens going forward. So as part of the upcoming update, I made a title screen that's animated from within the game, rather than using a video background, which should hopefully work for everyone.
With any luck, whatever the issue is with backgrounds not loading for you will be fixed automatically with all my changes to the code in the new update :3 But if not, I'll have to send you a development build and get you to send me all the error logs your computer generates to hopefully be able to figure out what's causing them to not load.
I don't know for sure, but I'm guessing the reason it will have frozen/crashed for you is because of some sort of conflict trying to access resources (like the backgrounds) that aren't there. Cos something like backgrounds missing is bound to cause other issues further down the line :(
As I mentioned, the revamp of existing content is now complete, but I won't be releasing the update until I've got the new content in there too. I'm aiming for the end of spring, but you never know what might go wrong, haha.
I'm sorry I can't be more helpful in fixing it for you now though >.< It's impossible for me to even try since that version of the game is now defunct and non-existent in an editable form. I didn't keep any backups of the old code just because I knew I'd be changing so much I wouldn't have a use for it anymore. I just hope that it all works as intended for you when I manage to release the update :3