[vunderba]

It's because it's not written in QBasic. It's written in a variant of QBasic called QB64 [1] - a spiritual successor to Microsoft's QBasic intended to run on modern 64-bit machines.

I went over the BAS source the last time this was posted a few weeks back and it has a lot of keywords that are specific to QB64 so unfortunately you can't run this on a true DOS machine (or DosBox).

[1] https://qb64.com

[stevengoodwin]

Worked second time for me (on Mint)

The first time it barfed was because there was a space in the filename, and the QB64 editor didn't handle it. Running on the command line, with quotes around the name, was flawless.

[bsammon]

However, it should be playable on Linux or OSX, both of which are (reportedly) supported by QB64.

[ianbicking]

I did give it a try, but no luck; qb64 seems to only run the code by compiling it via C++, and that failed on my system. (And I don't have the determination to try to find out why.)