Unfortunately, my first impressions are not good. I will happily change this review to a positive one if my personal experience improves. As a general note, I have only played as the Mechanicus so far.

First and foremost, I do not care for this soundtrack. It lacks all of the bombastic and memorable energy of the first game, and feels closer to the Ixion OST (which is good, but not 40K) than a proper follow-up to Mechanicus 2018. This is a bitter disappointment. I was really looking forward to getting another banger of an album. Again, I'll amend this bit later if it ends up winning me over. At least we can supplement this with the 2018 music using the DLC option.

Note: When using the 2018 OST, it plays back with a weird, sort of warbled effect. It sounds like the speakers are distant, or it's being passed through a noise gate? Maybe it's being ducked by another source in the game's audio? Really distracting.

Performance is bad. My machine is certainly not a supercomputer, but even on the lowest settings I can barely push 40 FPS. This is not that big of a deal for me, as this isn't the kind of game where rapid reflexes that rely on high FPS are present. Just a minor annoyance.

My big issue here is structure. I vehemently dislike the fact that your leader character is the lynchpin for every single mission. If they die, GG, game over, time to reset. This leads me to keep them back, out of danger and safe, but then they can't leverage their abilities and my fodder all die, leaving the leader alone and incapable of completing the mission. If I push them forward into danger to use their skills, even cautiously, the leader gets focused by all of the enemies and then they die. I like this idea in concept, but the execution is questionable at best.

I get that lots of people found the first game too easy due to tailoring your force in certain, very powerful ways, but it seems like the entire gameplay loop of the skirmish battles in this game pigeonholes you into a very specific style of play, which I have not really enjoyed so far. I hope that this aspect smooths out as I progress further and get a bit stronger. Who knows, maybe this will become one of those games that's notorious for a rough few hours at the start, then improving once you've invested a little time. I sure hope so.

Your performance on a given mission isn't tied to your rewards anymore, and coupled with the fact that every turn doesn't count anymore either (in regards to the Awakening timer mechanic from the first game), it gives the missions a really stilted feeling of objective over everything. No need to go the extra mile, no need to kill everything or tap into all of the data points (which are now absent, it would seem). Only the bare minimum.

I miss being able to pick and choose what rewards from missions I needed the most at any moment to prioritize what I did and in what order. I also dislike the linearity of the missions. The dungeon crawl aspect of the original was fantastic, and that's almost entirely absent here. I wish it still told you how difficult a mission would be before starting it, too. I do like the little narrative choices you get to make as you go, though.

The cognition system seems to be lacking depth compared to the original. It's not a puzzle anymore, it's a feedback loop of "did you bring enough Skitarii Rangers to play keep-away with the enemies and generate more than you need" every turn.

My last complaint is the lack of customization for the fighting forces. The upgrade trees are cool, but I can't really make the characters mine. I'm sure there's a few viable builds for all of the leaders, but one of my favorite aspects of the original was tailoring my squad to my exact tastes. I do appreciate that you can respec for free at any time between missions, but there doesn't seem to be much point.

Some positives do need to be said. The visuals are spectacular, the sound effects are punchy, the voice acting is great, and I'm glad we got the garbled speech option for the AdMec. That's fun. The artwork and character portraits are the highlight for me. Really nice work! The battlefields have all been stunning so far as well, really beautiful and atmospheric. I appreciate how you can drop pieces of the environment to use as cover, that's neat. You can even crush enemies beneath them. Fun! I also like the world map and faction management elements, but on the whole, I do feel a bit disappointed so far. I will carry on to give it a fair chance, but when your first impressions are this negative and you've got limited time each week to rack up hours in-game, it does make it a little challenging to stay engaged.

Feels like they took the first game, took away everything that made it unique/fun, and called it a sequel.

it lacks the fully customizable characters from the first game, the ability to freely navigate the tomb/map, as well as making all the missions a single linear story instead of a mostly open ended collection of missions you had to complete while racing against the clock

the game is passable as a standard 40k turn based strategy game like all the others, but that's not what mechanicus 1 was and I'm honestly disappointed.

While not perfect and fully true to the spirit of the first game, Mechanicus 2 reminds me of Darkest Dungeon 2- a game heavily connected to the first game, but vastly different with many changes that make it a sidegrade instead of upgrade. Which is not really a bad thing itself, but you have to be prepared for it.

Playing the beginning of the Necron campaign, I have to say that I dig the new upgrade system for them- more linear, focusing on equipping Relics and improving their cohort. This kind of system fits the Necrons, the idea of a single very strong leader unit commanding an army. It does not work great for the Tech Priests tho in my eyes, especially since Mechanicus 1 and its system of spending Blackstone to upgrade your Tech Priests and then having full freedom in how you upgrade them and equip them was superb.

The Mechanicus side of the game seems to lose the identity that was one of the selling points of the first game- total build freedom and flexibility. While I understand that the first game got crazy quickly and became too easy, the fact is that not being able to choose from plenty of different weapons for my Tech Priests saddens me deeply. The removal of Blackstone -> XP system also brings up a problem that was already solved in the first game- the power funnel. The more you use a certain character, the more experience it gets and the more inclined you are to stick to it, kinda killing your diversity of gameplay. I'd very much prefer for us to get points to upgrade our leaders that we could spend however we wanted and just unlock tiers over time, when your campaign progresses, allowing you to allocate resources across multiple leaders without feeling bad.

The combat is great, different from the first game- there seems to not be the armor/energy system anymore, instead we have a standarised Shield+HP+Damage mitigation, which I am fine with, it should make balancing the game easier and that's good, since like I said, the first game became too easy too quickly with its absurd combos.

The OST so far is.... good. Not excellent, not top of the top 40k or anything. The fact that you can BUY the first OST for this game to have it integrated kinda is a red flag to me that the composer and developer team did not feel that good with the new pieces, but I am hopeful to hear bangers when my campaign progresses further.

The tomb exploring and its random events from Mechanicus 1, well, tbh, I won't miss much, but that's me and my review. Linear systems with choices can also be great, as long as the choices matter- so far, they seem okay in this field, for example, having all your units deal minimal damage for 1 round because you picked a certain option feels like something that you have to play around.

Performance is okay for me, it doesn't look ugly, supports ultrawide and has a stable framerate. It is a turn-based game and I was okay with playing Baldur's Gate 3 on low graphics and in 15fps on my old laptop, so getting FPS below 120 and not having super detailed, hyperrealistic graphics does not bother me at all.

Tldr;
Solid sidegrade sequel, has its design flaws, but is a worthy position. Will it be a cult classic like the first game? Time will tell, it also depends on the updates and support. The new progression and mission systems are way more linear, which are okay to me, but I'd prefer the Adeptus Mechanicus to be the flexible faction with upgrades closer to the first game and the Necrons to follow this new, linear scheme via relics.

I'll update this review as my experience with the game expands, currently I can give it a cautious positive review.

Edit 1: Published initial thoughts about the game as a video- check it out if you'd a more in-depth first impression.
Link: https://youtu.be/bXUNcHZ5eNY?si=jasx28oreKaby1EO

Edit2: Played some more of the Necron campaign. My real in-mission usage of leaders is limited to 2 at the moment, the rest of them are side assigment bots that slowly get upgraded without me touching them. The Command Protocols and Relics and their symbol combos are neat as hell, that's the highlight of the Necron progression system. Playing with a leader called "The Shield" feels like it- I was worried that the requirement for each mission to have your leader survive and playing on Hard would be a bad combination, but if you play correctly, your tanky leader build can survive and thrive. For now, at least.

Some missions suffer from "Oh come the ♥♥♥♥ on, this is ♥♥♥♥♥♥♥♥" symptom of mission design via phantom reinforcements. I'd very much prefer for them to be shown beforehand, like at least a round earlier, so I could react properly on the first try- I know that Mechanicus 1 also had these, but trust me, the reinforcements in this game are WAY more disrupting sometimes. The first encounter with the Kastellan robot in the Necron campaign can be brutal if you are positioned near to it when it spawns. Overall, it is not a huge deal- I got wrecked 2 times in that mission, each time by getting surprised by a reinforcement wave spawning on my face. I can already tell that people wanting to beat the game on some sort of Ironman mode will have to use a wiki of some sort to remember where and when certain reinforcements spawn in some of the missions, because the difference between being close to them and on the other side of the map is night and day in terms of your winrate.