They say this fastest pseudo-random generator that is any good:
XorshiftYou need few lines of code to vary the mask, why not do this instead?
I read about and was intrigued by the two xoshiro256 algorithms and i think a great idea would be to create a xoshiro512 version that would be perfect for this application.
1) Expand the PRNG state from 256 bits to 512 bits
2) Seed the PRNG with all 512 bits of the point X that have been modified in a yet TBD way in order to create the various kangaroos
3) have the PRNG output a 256 bit pseudo random number based on the 512 bit state.
This might give better pseudo random coverage of the search space than my ultra simple (but faster) masking system.