I just started building an operating system that will be written entirely in one text file. This text file includes in order: a readme, a RISC-V assembly boot code, then the rest. You run it by compiling the initial boot code with a RISC-V assembler, then you concatenate the binary with the whole text file itself. Then when you run it, the boot code will compile the rest of the text file (the operating system), including higher level language compilers that the rest of the system will be written in.

This is the kind of project that creates something from as little as possible, where the only things you need to get started are a very basic RISC-V assembler and a computer or emulator to run it on.

I don't have anything interesting to show yet because I just started yesterday, but one day I will show you.