Unpacking a set of programs for Fido from exe (200kb) to an archive (2mb). How?

Question

Data archiving

I hope I remember everything correctly. In the late nineties, early 2000s, I downloaded a kit for Fido (Golded, T-mail) in the form of an exe-file weighing around 200kb. At startup, it took a long time (!) to unpack into an archive weighing 2mb. In what way was this achieved?

Answer 1

Or is it
https://ru.wikipedia.org/wiki/%D0%A1%D0%B0%D0%BC%D...
Or is it
https://xakep.ru/2012/10/29/own-exe -files-packer/

Answer 2

Obviously your question was how it turned out that 2Mb of data was generated from 200kb.
This is approximately akin to 64K executables, launching which resulted in entire worlds (I'm talking about this: https://habr.com/post/330090/ ). So, there, cunning functions are involved in the generation of all content, thus. function for 1 KB, but generates a 1 MB texture. It's similar here.
We just found such an algorithm, with such parameters, so that as a result of the execution of this algorithm with these parameters, the output would be exactly 2MB archive of the desired format.