On the topic of outlandish gravity ideas, I came across this video between Brian Greene and Neil deGrasse Tyson talking about how dark matter might not be matter but gravity leaking from another universe: https://youtu.be/1L6hinhDXQE?si=lfgOhk5phh88IMHO

Call me extremely dubious. Even if we grant the plausibility of the universe being a simulation, adding gravity (to the rest of our current physical laws) enormously increases the computational workload - due to vastly more, and more complex, interactions between particles. Vs. if memory is tight - just dial down the resolution a touch on all the hydrogen gas. Or simulate a smaller universe. Unless you're a big fan of cosmology, there is no sign of our universe doing anything particularly interesting at a "the whole universe" scale.

The universe is not a flash game. By combining particles into a small number of large "objects" this doesn't reduce computational complexity. Every particle still must be simulated independently.

I always thought it to be the other way around. If you assume that we are living in a simulation, then gravity might well be an artifact of a simulation that runs on localized, loosely coupled nodes. Because when you have mostly empty space, with low interaction, then the simulation is able to run at full speed, but the more particles you have interacting at close range, the slower the simulation gets as the local workload increases. In this model the force called gravity would not be the source, and time dilation one of it's effects, but instead time dilation caused by interactions is the cause and the gravitational force is what we experience as the result.