A short episode with 5 maps + 2 secret maps. There are too many small changes to weapons and enemies to list them all here. The most impactful changes are, that most weapons have magazines and need to be reloaded, they have a faster rate of fire, and you can switch weapons instantly (but can't cancel reload animations). This allows you to empty the magazine of one weapon, then switch to a different weapon and continue firing without interruption, typically finishing with the SSG.
I played this on "Tough", which is the equivalent of UV, and then again on "Extreme", which is more like UV++ instead of Nightmare and is intended for a second playthrough when you are familiar with the gameplay changes. With a bit of practice, I could beat all maps on Tough without saves. On Extreme? Nope... But it was a good challenge, for the most part, and I was always eager to try again.
New gibs and blood effects.
The Poison Elemental spits poison clouds instead of Lost Souls.
And Mancubi shoot a slightly different pattern that is harder to dodge.
The new Barons have a rocket launcher arm that falls off when they are below 50% health.
Fire Archviles, or whatever they are called, ignite the floor beneath you. They aren't as dangerous as regular Archviles. Just keep moving and don't run backwards into the flames.
If you look closely, you can see 50-100 Imps in this screenshot.
The new Scrap Gun is like a projectile shotgun with high spread. Very powerful up close, it fires 4 quick shots before reloading. It's an excellent tool to break through a horde of Imps, or to kill Cyberdemons.
It's unfortunate that the new/redesigned weapons all look too similar. The Scrap Gun looks like an extended SSG. And the Assault Rifle (re-skinned Chaingun) looks similar to the normal Shotgun. It's a bit harder to tell which weapon you have equipped, at a glance.
I hope you like the color green.
I need a new CPU to play Doom.
This ... is the worst fight in the game. Archviles continue to teleport in, and to avoid the burns you have to hide in the holes (like a real Doom Slayah), then push a button to raise the platform and climb out again. Sounds cool on paper. Except, the holes are too small and really hard to fall into, even with shift-walking. You have to run into those ledges from the right direction, and you have to be quick, no margin for error, while you are blinded by flames and blocked by Imps, Hell Knights, Revenants, and Spectres. I should have saved more rockets for this fight.