I think theyre suggesting hashing all of libgen and distributing and working backwards from that hash, as a joke
For something of the size of half life 3 (about 2GB? no idea), the number of collissions would be far more than the number of atoms in the universe.
Almost a "Graham's number" level of understatement.
Imagine something like finding the seed for a pseudorandom number generator where the numbers generated form the byte pattern for libgen.
That's similar to the cryptominer hashing where people just have rigs enumerating through possible values to generate a hash with the appropriate number of leading zeros. It's just that libgen would be little bit longer than a hash and also have some ones interspersed with the zeros.