Beyond the Reach of God
Note: I'm an atheist who, like you, agrees that there's no divine plan and that, good or bad, shit happens.
That said, I think there's a hole in your argument. You're convincing when you claim that unfair things happen on Earth; you're not convincing when you claim there's no afterlife where Earthly-unfairness is addressed.
Isn't that the whole idea (and solace) of the afterlife? (Occam's Razor stops me from believing in an afterlife, but you don't delve into that in your essay.) A theist could easily agree with most of your essay but say, "Don't worry, all those Holocaust victims are happy in the next world."
The same holds for your Game of Life scenario. Let's say I build an unfair Game of Life. I construct rules that will lead to my automata suffering, run the simulation, automata DO suffer, and God doesn't appear and change my code.
Okay, but how do I know that God hasn't extracted the souls of the automata and whisked them away to heaven? Souls are the loophole. Since you can't measure them (since they're not part of the natural world but are somehow connected to the natural world), God can cure unfairness (without messing with terrestrial dice) by playing right by souls.
My guess is that, like me, you simply don't believe in souls because such a belief is an arbitrary, just-because-it-feels-good belief. My mind -- trained and somehow naturally conditioned to cling to Occam's Razer -- just won't go there.