* Double chainsaw upgrade, specially if you can take it from the Doom Hunter.

* Maybe some BFG upgrades too like alt fires, because why not.

* Quad shotgun upgrade (Not an SSG with four barrels but rather an alt fire where you'd put two additional shells for more damage, otherwise the former could lead to a boring longer reload time).

* Pain Elementals based off Doom 64 with a third mouth (Yes, they're already back, but make it a subspecies or a miniboss)

* Chainsaw enemies (Was a thing in Doom 3 and 2 RPG but still)

* Since liquids were a thing in Doom levels but only as floor textures, i wouldn't mind seeing some swimming sections under water (or blood, acid and even lava) inspired by the likes of Quake and most Build engine games, but without an oxygen based system and we could see some hell fish enemies.

* A level (secret or not) based on Egypt, because so far there's only one level in this series with this theme and it's one of TNT's secret levels, which is unbeatable due to a bug that makes the yellow key disappear.

* Speaking of TNT, there should be an easter egg where a truck as TNT written on it.

* Final Doom: TNT's story implied that the demons had their own spaceships, which were made of "steel, stone, flesh, bone and corrution", so i'd like to see that happen and get shown, because why not?

* Some ideas taken from the Doom bible or any other unused concept, like the dark claw, because it could be neat if there was a new weapon that was some demon's hand if done right (Speaking of the Doom bible, those unused treasure items could make a great fit for another arcade mode since there's a life system already)

* A hellish weapon in general, like the Unmaker.

* Secret levels, that are actual new levels that fit the game's universe, which was something that happened in a lot of old FPS games and was done right (Duke Nukem 3D is an example of what i mean), so it could help to expand the game's universe.

* Earth needs to look varied and colorfull (But not too colorfull) to avoid the mistakes of the cancelled Doom 4 and help to make levels interesting (I can already see this being made).

* Speaking of variety in the levels, hell could get something like this too and if they can't make up new props or something, they could borrow more elements from the classics (Which they already did with the skull switches for example) and make them fit the game's version of hell (Evil eye, eye switches, floating rocks with skull, skull computer switch, FIREBLU?, mix of flesh and bone and metal etc), since some of this stuff can be considered iconic for Doom.

* Doomguy's HUD mugshot making a return, specially since QC confirmed the Doom Slayer is the classic Doomguy and, again, it's also iconic.

* What ever new enemies, weapons or twists for those that existed before they could pull out.

* Heaven?

* More of the Night Sentinels and their history.

* Maybe finally getting the Crucible as a weapon.

* Holy water pistol.

* A cyberdemon with two arm cannons and metal legs.

* A "techless" Cyberdemon.

* An easter egg referencing Heretic/Hexen, as a tribute to those games.

* And since the Doom reboot was taking many elements throughout the FPS genre, maybe a Wraithverge inspired weapon, that shoots homing (Lost) souls or a take on the Tome of Power to reference these games.

* An inclusion of Crash and Phobos from Quake 3.

* Bringing back the homing rocket for the Revenant or at least give a similar attack to another monster.

* Take some weapons from the multiplayer and put them in the singleplayer.

* Bringing back the Mancubus shooting TWO fireballs at once.

* On harder difficulties, armor functions more like its classic portrayal instead of being a second health bar.

* The possible DLC expansions to take inspiration from Final Doom, 64, the RPG games and even unused ideas/concepts for the games https://redd.it/9jhoaw

* Tei Tenga as a place with levels.

* Icon of Sin boss.

* More Marineguys.

* Maybe bring back some Doom 3 designs, since they were interesting.

* Recreation of the Cyberdemon vs Spider Mastermind battle from Doom 2's Map 20 Gotcha.

* Making the multiplayer as a seperate download from the singleplayer.

* Secrets that require the use of the meat hook.