The Citadel

Pretty fun boomer shooter with unique gunplay mechanics, especially if you grew up with the OG's. Lots of reviews call it a "gooner shooter," but those are probably the same types who never watched Ghost in the Shell or Elfen Lied because they think even a minutia of exposed skin means people are gonna blow a load like they're Mount Vesuvius from the exposure.
I you enjoy good character/sprite designs, or a "show, don't tell," story format, this is also a good choice. If you enjoyed, be sure to check out the version 0.4 demo of it's sequel: Beyond Citadel

This game definitely has some flaws, which other people mentioned in their reviews, like technical issues and in general not very good level design, but the strenghts of this game easily will take front and center, notably the excelent gunplay, great sprite work and moody atmosphere. If you like boomer shooters and have played quite a number of them already - you will be able to appreciate this game and have a good time!

I really can't express how refreshing The Citadel was. Like a breathe of fresh air in the industry. Only thing I didn't like the occasionally crashes but that was more due to the engine and not the game itself.
The passion of the developer is put on full display here with clear inspiration from other first person shooters, mainly doom.
Everything from Level Design, Gunplay, enemy variety and mixups, make for a great experience.
There are a few technical issues due to engine limitations and there being too many features and buttons for a gamepad but you can work around it with bindings. Just be aware you won't have access to everything. I highly advise playing this with a Mouse and Keyboard instead of a gamepad.
At max difficulty, it almost feels like a different game. Goes from fast paced Doom with tactical elements to SWAT 4 in a good way. Highly recommend saving a max difficulty run for last.
The artstyle is definitely anime but mostly just has violence front and center. Some folks don't like the gore but it's not any worse than mortal combat or Doom Eternal.
High Recommendation from me.

I'll address the elephant in the room. Is this a coomer boomer shooter? Not really. Aside from the main character there isn't much fan service in The Citadel. If anything, it's anti-fan service. It's eerie, grim-dark, and very violent. While enemies do appear as anime girls once killed, their guts are very detailed and the remains have horrified looks on their faces with tears rolling down their cheeks. There's almost no story within the game and it ends very abruptly. You have to search for it on the internet for some reason. What you can find is pretty interesting, at least.
Gameplay wise on one hand it seems to be a boomer shooter with double jumping, no fall damage (outside of instant death pits), no hitscanners - all projectiles, on the other you have iron sights, weapon recoil, leaning, and even manual and tactical reloads, as well as headshots... and then you pilot a mech and start blowing sh*t up.
The Citadel looks like a Wolfenstein 3D clone, but many levels have a ton of verticality where the double jump is required. Non-stop cyan aesthetics of the maps, in addition to featureless rooms, make them tiresome quickly.
There's no tutorial; the developer doesn't inform you e.g., what food exactly does, you have to figure it out yourself, and no quick saving. Only checkpoints with a life system. Very annoying due to platforming with instant death pits.
Tremendous potential, especially the setting. Since the sequel is in development, I hope it's much better.

Looks can be deceiving - even in videogames.
When I got this in a retro shooter bundle, I thought it looked by far the dullest of the bunch, just judging from the screenshots. The screenshots looked all very similar and it felt overall, frankly, quite boring and average, hence it's the last one I played of that bundle.
However, it is far from being dull. It is probably one of the weirdest retro shooters I've played, and I do play a lot of them.
It's only dull visually, as the textures are very basic and it all looks very samey across the 6 acts.
For the rest, it tries really hard (and most of the times it succeeds) in being original, in a very odd way.
Most things are really weird. The weapons. How you reload them. The UI is weird (in a bad way). The level design is also slightly odd although in a kind of a good way. The characters deserve a special mention for weirdness as they are some kind of anime which I guess might be entertaining to some but I just find them bloody weird. The music? Also very weird as half of the time doesn't match what's going on and it would be rather best placed for one of those "relaxing games" which seem quite popular nowadays. Performances are also weird as frame rate is quite inconsistent especially in a later level with many glass walls.
So considering all this: if you have played the great retro shooters of the current revival (everything from New Blood, but also Ion Fury and many others), and the classics of the previous era (Blood, Doom and mods, etc), and you don't mind the weirdness, you will probably have a good time with this. Just be aware it's quite hard, but if you played the ones just named you should be fine!

Cool and interesting stuff in all aspects EXCEPT level visual design, some bosses and your general overpowerness even on hardest difficulties. Micromanagment with weapons reminds me of System Shock which I very love.

It's not a boomer shooter, it's not a movement shooter. It's a "Do what is needed to finish the level" shooter, we need more of those.

I give it a Underbarrel-mounted Flamethrower/The screams