In this project, I write program for an AVR microcontroller in binary. I write the assembly instructions and then assemble it to binary by hand. Then I have my spreadsheet which is preloaded with formulae that calculates the addresses and generates the hex file which I can directly burn into my microcontroller. No text editor, no compiler. Just a datasheet and spreadsheet. It doesn't sound much interesting, but it proves the point for beginners that everything in the end is just 1s and 0s.
There are 2 sheets. In the first sheet, I type the actual instructions (The assembly is only for reference. It is not computed [sadly]). Only the green area is manually typed. All the other ones are computed from formula. The 2nd sheet does some background work to keep hold of temporary stuff along the calculation.
Interestingly this whole project doesn't use any macros. Just formula.