Alternative solar system generators?

[MOARdV]

Is this something: https://en.wikipedia.org/wiki/Nice_model

[MOARdV]

Maybe find a way to simulate gas giant migration?

[MOARdV]

Or, another possibility: the accrete model does sequential accumulation (the first protoplanet sweeps up all the dust it can before the next protoplanet is generated). What about generating many protoplanets (for some TBD definition of "many") and run each one through a single accumulation step before the next one gets to run. Maybe use a fallback of sequential accumulation at the end if the dust hasn't been adequately thinned out.

[MOARdV]

Moving the 'parallel' accretion model to a separate issue, and keep this one to track maybe a simplification of the Nice model.