Ooooh, boy... that's... yeah, that's definitely not good cos that sounds like something I would have no idea how to fix T_T
Whyyyyy do computers have to be so weird and temperamental?! >.< This is the sorta stuff that makes me want to throw things xD Why can't things just work for everyone, haha.
If it happened for everyone, it would be way easier to find the issue and fix it, but since it works for others, that means the problem is something specific about your system & the game files that doesn't gel, and finding out what that is could be hard, unfortunately.
If neither version of the Windows build works for you, the regular one with video backgrounds or the non-video one, I can't even begin to think wtf would cause it to do that :(
Especially since you said you do get the splash + music cos that means that Nani has initialised. It must have started loading the title screen script cos one of the 1st commands in the code is to play the BGM, but then it has somehow stopped loading the script before loading the background, and worse than that, rather than skipping it, has basically aborted the script entirely if the title screen buttons don't load either >.<
Cos the stop command for the script to end is as soon as the buttons load so that players can click whatever button outta start/options/quit.
If I had to guess at all, there must be something your computer really hates about the background file cos it probably ran into an issue when it tried to load that for whatever reason, then aborted the process T_T
I could just about understand why if it only happens on the version with MP4s since I've been told encoding of videos can cause all sorts of problems across different PCs where some will be fine & others won't.
But if it happens on the non-video version that has 0 mp4 files and only uses pngs for backgrounds, then I am 110% baffled >.<
Literally the only way I could even begin to figure out what's going wrong would be to export the game as a dev build, have you launch it, and then have you send me the error logs that I could pass on to the Naninovel software devs for them to look into.
It sounds like one of those strange issues that I wouldn't be able to identify alone :( But if they look at the logs, they'd probably be able to figure out what's going on and possibly advise me on what I might be able to do!
This sorta thing seems to happen a lot cos when I browse the Naninovel support on Discord, I end up seeing devs saying that X part of their game works fine for 90% of players, but 10% have X issue and they don't know what the heck is causing it >.<
The even more frustrating thing though is that I can't export a dev build to get any error logs from you because I doubt the potato could handle exporting Unity builds T_T so I'd have to wait until I have a proper PC again >.<
Edit: Also, thanks for playing YH btw!! :3 It makes the issue even weirder if that ran fine >.< haha. Cos YH is the only game I've ever had someone describe that sorta issue with where the title screen buttons don't pop up and there's a blank background.
Cos even when DD used to have a video background that caused certain players problems, afaik, it still loaded the buttons at least, just not the backgrounds >.<