I realized that the .p8 files alone result in missing #include directives, so I updated the zip, with the .p8.png files now.
Viewing post in Murder Drones Virtual Training 2: Sand & Steel [DEMO] comments
For me, it works placing all the `.p8.png` files in a folder in the cart directory. In Linux this would be:
~/.lexaloffle/pico-8/carts/mdvt2_p8carts/
Then in PICO-8:
> cd mdvt2_p8carts > load mdvt2.p8.png
I don't know how you can set the working directory (`cd` command) in an emulator handheld. If that is not possible, you might need to drop all the carts at the top-level.