Originally Posted by BillyBobTwo
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.
Exactly what I needed to know! Now I can actually start playing the damn game, rather than inquisitively staring at the main menu. Human it will be! Thank you, my friend.