Please let's discuss what kind of feature we actually want to use. I don't want to add things that no one wants to use.
Bear in mind that the features are all tentative, not definite. And they all works for single model only. The goal is to make the model more like a friend to you.

So far the things I can to do in this program:
* Create personal play lists so I can play the songs I like. I can save and load the playlist to suit my preference at the time.
* Add personal assistant features like voice alarm clock, which will perform certain dance when the set time is reach, or speak something when you have new emails, or browse certain websites.
* Be shy or trying to dodge the mouse cursor. Or be attractive and saying some nice words when the mouse cursor is over the model.
* Snooze when no mouse cursor is over the model for a long time.
* Automatically walk to a empty desktop place if a new window is open.
* Conversation in text bubbles. ( This needs lots of work to find the model's actual position data, but still can be done.) Hourly jokes.
* Play happy, sad, surprise emotions when speak certain things.
* Automatically dance when music is played. But I am not sure how to distinguish music from normal sound. Or maybe just a "Dance/Stop" button is good enough?
* Steamdeck and shortcut key support.

This is actually great news I've been waiting to hear. I think in the meantime you may release your version of this software on Steam. There are not many people using this software or being available online either. So, your news only reaches a very few people. The former developers betrayed their customers for the things they promised could not meet end users' expectation and since then it received a lot of negative reviews and this software had become an abandonware.

If I recall there was an unofficial discord about this software, you could find the link to join from the workshop posted by a very proactive dedicated fan in the past. If you manage to join that group then at least you can have more supporters to your current project as well as connect to more non-English people.

i hope you keep working on your project and avoid getting struck by any copyright infringement

I think in the meantime you may release your version of this software on Steam. There are not many people using this software or being available online either. So, your news only reaches a very few people.

I am releasing on Github because I don't think Steam is the right platform. The helper is all open-source. This way if people want to add their own functions, they can. I just lay out the ground work for them.
At the same time, I don't really want many people to get this program. Only the people who cares about MMD3 deserve the benefits of the helper.

The former developers betrayed their customers for the things they promised could not meet end users' expectation and since then it received a lot of negative reviews and this software had become an abandonware.

I hold quite a different opinion about why the author abandoned this software. Maybe because I am also a small-time programmer. I can sympathize more with his experience.

If I recall there was an unofficial discord about this software

Really ?! I will check it out!
Update: Sorry, cannot find it. Many MMD discord channels, but not one is for DesktopMMD (3).

i hope you keep working on your project and avoid getting struck by any copyright infringement

Thanks for the advice!! This is exactly why I host it in Github. The program is GPL v3. I am not in any trouble, and I hope you will enjoy using the helper in the future.

The first version will enable the models to dance with a full-screen background picture. Other features will be added one by one in the future.

Update:
* Just found a way to get the position of models and get notified if a model is removed. It will greatly simplify my programming.
* Combine the position with the Zoom scale info, I can calculate the rough position of a model's head, which I can use to put a text bubble near it. So the model can be your friend and talk to you with text bubbles.
* It's possible to load DMMDCore3.exe without running DesktopMMD3.exe. I can write a host program to directly control DMMDCore3, but of course this is really not good. A step too far.

Update:
* Switched to tray-menu based program. It can sit in the tray with MMD3 running or not. Once it sees the MMD3 is running, it will automatically change its status.
* The basic structure and the hooks procedures are done. Now it's time to make those buttons really work.

Update:
* The menu system is set. Now working on detecting models that were loaded. The model list is not accurate if you run MMD3 first, but at least it works.
* For some reason sending the model command is not working again. Need to find out why again.
* More details are in the Github repo:
https://github.com/philpw99/MMD3_Helper

Update:
Last night for the first time I play a dance with a scenic background and snow flake effect. It's pretty cool ! Love the way it changed the whole dancing experience.

Well, I will put 20 backgrounds and 20 effects in the release, and the default is that it will show a random background with random effect whenever a model or models start dancing.

If the dance file contains extra Backgrounds and Effects settings ( extra.json), it will read the file and show the backgrounds and effects according to it. You can control when to play a certain background and effects. The combination is limitless.
Video background is not a good idea, because of the huge size. I think high resolution pictures are already enough.

Update:
The MMD_Helper will also support the upcoming DesktopMMD4.

heh was just about to make a post on here about the mmd4 that is coming out. keep up the awsome work. this one may be the one i stick to anyways if the hardware requirements end up being too high lol

Actually MMD4 requires a lot less resource than MMD3. MMD3 can show highly realistic model, while DME and MMD4 are targeting more toward Japanese anime style.
MMD_Helper version 1 is basically done. It will come with 20 backgrounds with special effects. Just need some packaging.

ah cool ill keep both then because i like the real and anime models the mmd4 steam workshop will probably less than mmd3 at the beginning anyways. ill get it on a sale

The good news is that, if you have MMD3, then you will get MMD4 for free. 😊
Also now MMD_Helper is updated to v1.0.1, added better image support.

yay :D that is good news and I saw i will check it out myself when I have the time ^^

Is it possible to make the model dansce at random when using a random mp3/ogg etc .?

That's already done if you use WinAmp. MMD3 can monitor WinAmp and make models dance if a song is played. Other players includes Spotify, CloudMusic, Foobar 2000, XiaoMi, QQMusic and VLC.