This is just a note for making the point that it might be possible to write computer code to make a Universe expand from a singularity with much detail of various processes. Probably its already been done countless times in physics science labs. I am not aware of a popular video game with adjustable, variable parameters for modifying one’s designed Universe though.
I believe that a spherical gravitational collapse of a scaler field, arriving at t=0 is a paradigm comparable to quanta of the cosmic microwave background running in reverse to an inflation and singularity if one posits a phase change and radical deceleration at the inflation. Physicists have a lot of data and probably model algorithms for the expansion consistent with observable properties of the universe. Perhaps there are numerous algorithms exploiting observable quanta and fields that would reach t=0. Recent papers suggest the Universe is one-off rather than cyclic.
There are some very exotic theories. Fun to look in to; phases changes and inflation etc. At time=0. There was a lot of anti matter too, and mass only formed after the weak force, Higgs field and electro magnetism seperated from the electroweak force, preceded by the strong force and gravity first. If there were no mass perhaps gravity hadn’t anything to act up on, and during that moment inflation occurred?
Garrison Gibson: books and blog 