Ranks are all locked to their difficulties, so to get the achievement for getting SSS on Nephilim you need to be playing on Nephilim. Ranks do not retroactively update if that is your question. Meaning getting a SSS on collectibles later will not upgrade previous ratings. To get all the collectibles you need to get to at least mission 6 to get Eryx.
So you can play on Nep to start but you are still going to have to go back and re-do the first missions anyway so it's up to you if you want that time to be easier or harder. Also Keys for Doors do not match up one for one. Meaning you might get a Copper Key in a mission, but the door is Argent.
It just seemed easier to get everything unlocked, then get all the collectibles, and then really get going in the game. That was just my take on it.
Any of the three starting difficulties will unlock Son of Sparda.
Originally Posted by x RadicalAura x
For those of you who have made decent progression in this game already, would you advise following BillyBob's roadmap as far as difficulty progression is concerned? Just got home from work and I'm just about to get started on my first playthrough but not sure which difficulty to start off on. I have played all four of the original DMC games, so I'm not reluctant to start on Nephilim at all but that's not what BillyBob advises. Does anyone know if you just have to complete one playthrough on any difficulty to unlock Son of Sparda or does it have to be completed on Nephilim? Also, are collectibles and SSS rankings retroactive in the sense that if I get SS rankings on all levels on Nephilim and then dedicate a separate playthrough on Human for collectibles, I will then be awarded the SSS rankings on the Nephilim missions I had completed prior? Or do the collectibles have to be completed before even thinking about going for the Nephilim SSS achievement? I'm just trying to figure this out for efficiency's sake with collectibles and all so I don't have a bunch of extra needless playthroughs (not that I don't want replay value)! Thanks in advance.