Comment by Y_Y

You're right that the time delays and redshifting wouldn't add much to a toy app, but some of us are here for the physics.

Honestly it's not so far-fetched (to me) that in a few years someone will have GRRMHD simulations running in real time on a portable device.

Are you familiar with A Slower Speed of Light? It's a game which has some nice special-relativistic effects.

http://gamelab.mit.edu/games/a-slower-speed-of-light/