Every iteration on gameplay code costs you the same tax: stop Play Mode, wait for the domain to reload, replay the setup, get back to the moment you were testing. RuntimeCode removes that loop. Save a file while the game is running and the change is live in under a second, with your scene, your position, and your serialized state intact.

What It Does

RuntimeCode watches your scripts, compiles the changed file with the same Roslyn compiler that ships inside your Unity installation, and puts the new code into the running game. Because it is Unity's own compiler, the language level is whatever your Unity supports — records, init-only properties, switch expressions and pattern matching all compile.

Two mechanisms, chosen automatically:

• Method patching redirects the running method in place. Instances are untouched, so

everything on them survives: fields, coroutines, event subscriptions, Update state. Available on Windows, Intel macOS and x64 Linux.

• Component replacement rebuilds the affected components from the new type and carries the

serialized state across. Available everywhere, including Apple Silicon macOS.

The package tests which mechanism actually works on your machine at startup — it patches one of its own methods and verifies the result — rather than assuming from the platform name. If patching is unavailable, it says so plainly and falls back.

What You See

A single editor window shows the compile result, the reload strategy in use, and a log of every reload with its timing. Compile errors appear with file and line, in English, in the same window — you do not go hunting through the console.

What It Does Not Do

It reloads method bodies and component code. Adding a field to a MonoBehaviour changes the serialized layout, and that still needs a normal domain reload — the window tells you when this is the case instead of silently doing nothing.

Verified, Not Assumed

174 automated tests run against a real Unity editor before every release: 147 in EditMode and 27 in PlayMode, including a full live reload cycle with the domain reload disabled, as Unity 6.6 requires.