Normally these demos are filled with all kinds of 'tricks' to make things smaller.

Things like self modifying code, using bits of the bios or video ROM in ways they weren't intended by jumping into the middle of them, saving space by using code as data or vice versa, tiny packers which compress or uncompress the code, massive pregenerated buffers to do runtime lookups to generate data in one order but use it in another, etc.

This seems very vanilla in comparison...