v4.2.1
- Add support for practice (undo/redo), this feature is beta and not guaranteed to work in live play
- Add the Amber JS deobfuscator to automatically parse and run the TETR.IO custom codec (binary transport)
- Improve the speed of the internal game engine by ~3x
- Improve the speed of the replay test suite by ~10x
- Many other misc bugfixes/improvements