I've always wanted to build my own computer system, OS and all, which would be, ahem, perfected. I designed an ISA called SubSky and wrote an emulator/VM implementing it, and made a language + compiler. (It's kinda like UXN in nature, actually, just 32-bit and more 2000s-era than 80s-era.) A 16-opcode, 3-operand RISC with an operand/"pseudoregister" referring to the stack. I'll have to publish it sometime. I'm making a videogame for it.

Cc: @rl_dane (it didn't seem right to reply to the thread)