Harbor

RuneLite changed how people play Old School RuneScape: quest guidance, highlights, and menu swaps built right into the client. RuneScape 3 never got an equivalent, because RS3 runs on NXT, a native C++ engine instead of Java. Harbor brings those quality-of-life plugins to RS3 anyway.

A C# launcher starts the game and loads Harbor’s C++17 core, which hooks the DirectX 11 and OpenGL render path to draw ImGui panels and depth-tested world markers inside the game’s own frame. A Qt 6 sidebar gives it the plugin list and settings panels RuneLite players expect.

Everything Harbor knows about the engine is mapped in proof-gated definitions that generate the C++ headers, so nothing ships until it’s verified against the live game – and it keeps working when the game updates. One profiling pass traced a 160 → 100 FPS drop to a hook firing about 4,300 times per frame; taking it out of player builds won the frame time back.