I think quasars would be a cool new feature for this simulator and i think it is possible to simulate them.
While i don't know everything about the physics behind quasars, i do know about the accretion disk and relativstic jets.
Maybe it is possible to simulate quasars like this:
A black hole sucks in matter (planets, stars etc.), but right before the matter disappears, an accretion disk and relativistic jets appear.
I dont know how much mater a black hole needs to suck in before it becomes a quasar. Neither do i know how long these jets and the disk last. So the simulation i came up with is obviously not polished.