Introduction
Let's get started. First, you’ll need shared or virtual web hosting with PHP support and S3 storage, as well as the Eclipse IDE and the Liberica JDK development tools. You can choose any version of JDK 8, since they are all forks of OpenJDK. For variety, I’ll also include a link to Azul Zulu. You will also need RetroMCP to mod the client/server.
After installing IDE and JDK, you may proceed to next parts:
The order of these steps is not set in stone; you can test the launcher first and then proceed to modify the client. This is just a general guide.