Well, repeating the previous answer
> Game Boy app to explore 4-bit synthesis and "modular" sequencing, smth similar to https://roberthenke.com/technology/inside8032av.html but for Game Boy instead of Commodore PC
I always wanted to try MUD with creative mode, when player may create new areas/items/mobs using code and textual descriptions. Like Minecraft/Interactive fiction hybrid or AI dungeon without AI.