I have made a Discord server for Galaxy Engine! You can join here: https://discord.gg/Xd5JUqNFPM
These videos we created inside Galaxy Engine, an open source program that I'm currently working on. The video with the highest amount of particles is the Big Bang one, with over 2 million particles.
Here you can find the Github repository and executable: https://github.com/NarcisCalin/Galaxy-Engine
You can also download the program from Itch.io: https://narciscalin.itch.io/galaxy-engine
