The minimum requirement for Windows is to make it support 32-bit versions, unless 4+ GB of RAM or other x64-only features may be needed.
You've read me correctly, that IS the minimum requirement.
I already know that I have a x64-capable system, enjoying a bit of Riko4 on it, and I actually received a gifted copy of PICO-8 last year.
Update August 20th, 2018: Slight change to show 15 color rectangles instead of only 7. This is not a song-related change.
Credit to Zep for the code base.
I really want to play with these fantasy consoles on my 32-bit PC, but the only problem is that they only have official binaries for 64-bit Windows. I have no idea as to what compiler I should use to create one myself.
Please note that this thread has nothing to do with PICO-8.