I know this post is probably a big shock and not expected, but as said, all things have an end, unfortunately. I will try to explain everything as much as possible in this post.
There are more updated news around this here, as some parts of the future plans got changed and/or polished and better explained here: https://mcreator.net/news/67886/minecraft-116x-and-future-mcreator
I still remember the day my brother Matej (also developer, moderator, and co-maintainer of MCreator) showed me Minecraft and told me it is written in Java, this was all the way back in the days of Risugami's modloader. I immediately got the idea for MCreator. Since then, the project has kept on growing and becoming better and better, and the community got bigger and bigger, and things started to move faster and faster.
With its growth, there was more and more time needed to maintain the project and the community. In the past few years, I have become very overworked and have reached the point of burn-out, unfortunately. I have another job at a robotics company that pays and will pay the bills, while MCreator is a free project. Unfortunately, I can't maintain both of them. MCreator is time-wise-looking another full-time job for me. My day no longer consists of free time and I had to cut down on all other activities and things I love in order to be able to sustain MCreator while working and studying at the same time.
I was somehow hoping open-sourcing would improve this, but it turned out being an open-source maintainer, no work was taken from me, just additional work of managing pull requests and planning the work was added to the mix. I have big guilt that I gave a false hope with the open-sourcing move as many community members really bit into the opportunity and helped a lot with contributions and new feature additions, but unfortunately, I was not able to foresee the outcome of open-sourcing properly.
What will happen now?
I do not find it fair to just shut it down immediately, as many contributions from the community were already made, so I will try to work with the community to finish the MCreator 2020.5 update in the next few weeks. I will try to add some of the pull requests to the update, but will very likely not be able to add all of them, especially not larger ones. For this reason, I am also asking contributors to slow down with PRs to the official repository, as they might not all get into the update, to avoid any disappointments if I will not be able to merge them all.
I was hoping for a stable 1.16.x Forge to come sooner, but it didn't, so there likely won't be an MCreator update adding support for this Minecraft version (this is not definitive yet, it depends on the time I will have in the first university semester). After the 2020.5 update, I will eventually halt my development of MCreator software.
Open-sourcing might have given MCreator an option for a second life, on the other hand. Some members of the community and contributors might recognize themselves as possible future maintainers. I will keep the MCreator name, as it is part of my life, it is my child. But if there will be community interest in running the project forwards under a new name, new website, and new lead after the 2020.5 update, I will gladly support the new project by promoting it as a successor of MCreator on the website in the future. Keep in mind that I am quitting development entirely so I will not be able to offer any help on the potential future development.
I plan on keeping the website alive as the community is not dying with the end of software development. Matej plans on running mod of the week to the end of this year and making one final yearly recap video. I might be revoking wiki contributor and moderator roles in the future (depends on the need of them and the activity of the users having these roles) but will keep running the website for some time after that, and then once in the future (probably far in the future, depending on the activity of users), put it into the read-only mode.
I would like to thank each member of the community, we were an awesome family. MCreator's community is one of the friendliest and most supportive communities I was ever part of. Big thanks to moderators, wiki contributors, people who helped on forums, thanks to code and translation contributors, thanks to donors who helped me work on this project, thanks to all the people who were making tutorials for MCreator, and thanks to every single user of MCreator that was part of this story. I will be revoking monthly donations as I don't find it fair to receive any more donations from this point on.
I know MCreator plays an important role in the lives of many of you, and believe me, it is very hard for me too, especially after working on this project each day, even during weekends, for almost 9 years. It was a big part of my life and me growing up and I am writing this with tears in my eyes thinking back to all this. But as the title of this post says, all stories have an ending, and this is MCreator's ending.
It was an amazing journey, thank you for everything!
EDIT 15. 9. 2020
Thank you for all the positive comments you wrote. I am still reading them and will try to respond to them as soon as possible, but it is a really hard time for me right now. MCreator was all for me, but unfortunately, life has its own ways.
I noticed new versions started to emerge and I really like this. I would like just point out that naming new projects something like MCreator + adjective could be a bit confusing for users regarding the maintainership of the software. Ideally, I wanted the names to be something like XYZ - The successor/fork/next thing/ ... of MCreator. If you still want to use "MCreator + adjective", just make sure to clarify this is a new version and new software based on MCreator and is not MCreator itself. Naming it MCreator 2 or similar is not acceptable as this is still the original name and too confusing.
Another thing I want to clarify is that MCreator is licensed under the GPL-3.0 license, so all forks need to use this license too due to legal implications and need to be open sourced under this license. Make sure to understand all the requirements of GPL-3.0 when making forks and distributing them (including things like keeping the original copyright notice for the year 2020 and only adding new ones for the modifications of the source code).
Some users don't read all text and make assumptions and spread incorrect information, so here is a short summary for such users, excluding reasons and backstory.
In short, the software development will stop after 2020.5, the website and community will remain up, so will downloads and plugins, open sourcing allows others to make new variants of MCreator under new names. MCreator is not dead-ending, nor shutting down, but the development will be halted in the future. The software will still be downloadable and usable, the website will still be up, and the community will still be here to be part of.