It’s now possible to include .lua files, but PICO-8 seems to be very confused when they have CRLF line terminators, reporting syntax errors at weird locations.

Note that including .p8 files with CRLF line endings works just fine, but not if they have an UTF-8 BOM ( @Niarkou reported this a while ago: https://www.lexaloffle.com/bbs/?tid=31617). To summarise:

• .p8 with UTF-8 BOM: fail
• .p8 with CRLF: OK
• .lua with UTF-8 BOM: OK
• .lua with CRLF: fail

It’s not unusual to have CRLF line endings, even unwillingly; for instance, if I push a .lua file to Git from a Linux box (with LF line endings) then pull the file on Windows, by default it magically gets CRLF line endings. This can be configured but it may confuse users.