Jensen's overheating system has now a bigger impact in the main campaign as every upgrades of the experimental augmentations add +50 to the overclocking. The chaff upgrade now doesn't delay the grenades and mines too much (so it is an useful upgrade and not a nuisance anymore). Also, it isn't possible anymore to remain invisible when doing a takedown (melee attack).
Takedowns are more complicated to do but they use no energy at all now. Augmentations like TESLA, FOCUS and Cloaking which made the game very easy have been nerfed. Now when this augmentation is enabled, the player can stay indefinitively in an area where there is gas : He isn't limited by his level of energy).
The Rebreather augmentation now doesn't consume energy at all (So it is just like in Deus Ex Human Revolution). unless of course, he activates this augmentation (Like the 2 others augmentations above, following Jensen's visit to Koller). The Stealth Avatar augmentation is now disabled by defaut so if the player is detected and manages to hide himself, there will be no image of his last known position displayed on his field of view. The radar HUD doesn't display the targets anymore : It only displays the environment and the objectives locations. The Health Regeneration upgrade is now disabled by default but it can be enabled with Praxis kits after Koller resets Jensen's system (So, after the Dubai intro). The numbers of praxis kits necessary to activate Adam Jensen's augmentations have been changed (Basically most augmentations now require more praxis kits to be enabled so at the end of the game, the player will be more specialized).
Here is what the Hardcore Revival Mod for Deus Ex Mankind Divided changes when it comes to the gameplay: