It's the raw cerebral intensity of Quake married with Doom's enemy roster and its violent, cathartic attitude. Enjoying this game requires a certain frame of mind, a certain willingness to push yourself and to think in the heat of the moment. But it's extremely rewarding if you meet it on its own terms. Nearly every weapon feels like it has a significant role, a stark contrast to Doom 2016's promotion of 2 weapon playstyles. Ammo counts have been massively reduced, pushing the player towards intelligent use of their loadout. Overall, the way I would describe this difference is that Doom 2016 treats its weapons as a set of toys, in which any can be used at any time without too much consequence. Doom Eternal treats them as tools, and you have to use them well to achieve success.