I've got this game on PS3, and am going to be starting in on it here shortly.... as soon as I finish collecting feathers and getting Platinum on Assassin's Creed 2.
I got the "Are You a God?" achievement on Xbox 360 (gamertag: Agent 7k), and it was very, very simple. It only took a few hours. Maybe they patched it, or maybe it doesn't work on PS3, but here's how I did it:
-Beat game on easy/normal first, so that you can load up any chapter that you want.
-Beat the first chapter of a level
-Beat the final boss of that level
-continue on to next level
-beat that first chapter
-skip to boss of that level
-beat the boss, continue on, beat first chapter of..... well, you see the pattern here
Sorry if I'm overlooking anything, or I'm slightly off in my description, as I did this on X360 back when this was first released a few years ago. Again, it might've been a Xbox thing, and maybe it never worked on PS3. Maybe it's patched.
After I finish the game on easy, though, you damn well better believe I'm going to try this method, again......