OpenCraft 2 is a remake of OpenCraft for OpenMX that has music as well as the blocks of 1.21 (some have been removed for convenience and consistency). It was made in TurboWarp as it can handle uploading the 1000-something PNGs that the "/assets/textures/block/" folder in the Minecraft 1.20.6 JAR has without even crashing.
Credit to @bambus80 for the fullscreen app framework and Mojang Studios for the music and block textures. Left = previous block Right = next block Space = erase all blocks