So, uhh, yeah... I finally got The Real Platinum God in The Binding of Isaac: Rebirth (do and find everything).
Just like in the original Binding of Isaac, I spent a large amount of time after I'd done all the hard stuff just trying to get lucky enough to find the last few items. You need to get every item in the game to unlock the achievement, and some of them only appear under certain conditions, and rarely, at that. Steven was the worst of the bunch, requiring you to fight the rare version of a rare boss on a particular version of the first floor, and he only rarely drops the stupid item. I basically spent three days rushing the first floor of the Basement as Azazel and starting over if it wasn't Steven, and killing his ass over and over again and getting Little Steven.
I wish that getting every item wasn't a requirement for TRPG, because it's entirely luck-based and not super interesting.
Interestingly, it took approximately the same amount of time that the first game took to unlock everything. TBoI:R has way more content than TBoI, but my skills and knowledge from playing the first game were mostly directly transferable.
68 of these deaths were "legitimate." Once I got the three endings you need with The Lost, I just died with him over and over again to get up to 100 deaths so the scissors could spawn. I really wish getting 100 deaths wasn't an achievement, but hey, it's over now.
Let me know if anyone knows any fun seeds.