All this needs now is a New Game +

[Bryndor]

I've finished this three times now, once at launch, another after Patch 3 for the last achievements, and then a final playthrough with the challenge of not unlocking a single upgrade on max difficulty.
It was just amazing, but now all that I want is to play it again but without needing to get all of my upgrades for the fourth time.
Enemies being tough right from the start, having all the unlocks (except for things like the disguises and the lighter, but definitely keeping maps and adventure books), it'd be great to jump right back in but be able to use all of those upgrades right away, especially the late game ones where you barely get to use them before the credits roll.
I hope it's something that can be added upon the DLC release or something. Otherwise, 9/10 game!

[Paper Rival]

Agreed, would love to see a new game plus mode added for subsequent playthroughs.