[a1k0n]

Just because it doesn't have the ,1 doesn't mean it's written in BASIC; it could still be written in machine language with a BASIC stub that executes the actual code (which is loaded into the BASIC memory area but isn't necessarily BASIC) when you type RUN.

[nsxwolf]

This appears to be the case, as I do not believe it would be possible for the game to run with this performance level written in BASIC.