Lunar Client Qt is a lightweight, cross-platform and open sourced launcher for Lunar Client written in C++ using the Qt framework.
One of the primary features of this launcher is the ability to easily attach Java premain agents to your game, this allows you to modify the game on launch, which lets you write modifications that won't break when Lunar Client recieves an update.
Here's a repository containing some useful Java agents that you might want to use: https://github.com/Nilsen84/lunar-client-agents
If you're familiar with Java bytecode, feel free to write your own!
Make sure you have Qt 5.15+ and CMake 3.21+ installed.
git clone https://github.com/Nilsen84/lunar-client-qt.git --recurse-submodules
cd lunar-client-qt
mkdir build && cd build
cmake ..
make
NOTE
If you're on MacOS, you wanna start off by installing Qt using Brew: brew install qt@5
You also want to replace the cmake .. command with cmake -DCMAKE_PREFIX_PATH=`brew --prefix qt5` ..
Besides that, follow the same instructions above.