Remnant: From the Ashes is a visually decent game (considering it comes from an indie dev), that under closer scrutiny becomes mediocre at best and horribly frustrating at worst.
Most of the criticism is that despite this game advertisting itself as solo OR co-op, it is so heavily skewed towards co-op to have actual fun that solo just becomes a frustrating slog, at least to me.
Firstly, the game does not have a proper way to make the game playable outside of co-op. One of the most frustrating things is that the enemies are EVERYWHERE and playing solo this will have you turn 180s every other second. 70% of the game is being assaulted from all directions. It's like those annoying bow snipers in Souls games. Just that there they are either an addition to a navigating challenge to beat them or it's just a few and you can reliably dodge them until you get near them for the kill.
Here enemies will be constantly in front, in the back, to the sides and they are ranged, so there is a constant stream of projectiles from all sides hitting you while you just try to kill them one by one. Even better if you went for a melee build, because some enemies and bosses just invalidate that. Which brings me to my next point.
Builds, again, are centered around co-op. As a solo player you are basically limited to 2 guns with 1 ability each. Amazing. Such build diversity. And guess what? Because you are a solo player, you are gonna have to have at least one of those abilities geared towards survival because of the aforementioned tedium of enemy bombardments. So for build diversity you get...one ability slot. One. Such great synergy potential here. Amazing for a game whos whole combat is already basic and then all that can sweeten it is one ability you can actually freely choose.
Bosses range from being just ok, as in mediocre, to again being a chore without co-op. You have bosses that are literally split in 2, one on each side and designed so you can't see both of them at once. The problem? Both cast high damage abilities regularly. With a QUICK animation speed. So as a solo player, you have to constantly 180 like a madman. This is clearly intended for fun co-op teamwork on discord to go like "bro, there is a beam/swing coming other side" "kk, thanks". With solo, you will just take almost inevitable damage unless you really start spinning around and still keep track of things.
Additionally, bosses are just ads. Ads without end, ads that will spawn behind and in front of you. Ads that will interrupt you, stagger you, stunlock you, if you dare focus on the boss without spinning around to check how far they are away first or killing all of them to get a 7 second window before the next batch comes.
SPOILERS FOR THE FINAL BOSS:
The final boss has 1 attack. One. A single one. And it's basically a oneshot if you get hit. The rest is just killing ads, ads, ads. Amazing and very fitting end to this game. Also, unmentioned mechanics. Also, forcing you into one specific build to beat it efficiently and not take 20 minutes. Also, it can just instacast said oneshot attack while you are still being transported to and from the ad realm, almost guaranteeing a oneshot if you don't instinctually start sprint the moment you spawn.
The only actual thing that was good about this game was that there were a lot of enemy MODELS. As in, visual models and their animations. Meanwhile they basically all do the same.
Lastly, the lore: God, it's disjointed and so generic. And rather incompetently written, at least in my opinion. The beauty of soulslike games is to tell their story in snippets and engage you in what's going on. For example, in Elden Ring you will have item descriptions of key items like "Over time the Erdtree became more of a religious symbol than a physical object of worship" (paraphrased). Things like these are well written because they convey important information concisely and every word NOT said is also important.
Meanwhile in Remnant: From the Ashes you get things like "Captain soandso from the vanguard of the soso fought the root in the x dimension on y time while z was going on on earth, showing a connection from the Root to the Guardian concerning the Universe of the Dreamer at the occurence of the whocaresanymore."
Like jesus. Way too much. Way too many invented words. Way too much clutter and overexposition. A situation leading to you not knowing even the basis of what the description is trying to say. You having to read another 100 descriptions of the same overcluttered type to try to understand it. It's not fun to immerse yourself in lore that is so poorly written and just infodumps on every occasion. The fun is tying concise descriptions together, not just having 50 that blast your face in with invented words, most of which are nowhere seen in dialogue.
Also, please just don't make my character talk. At least not like this. It made me really wonder who this game is made for because my character just keeps saying shit they would say in a marvel movie. Like "oof, that was a close one, huh" or bantering the enemies. As a mid 20s guy, it felt like I am playing fortnite, honestly. It's like my character in the midst of a dark souls fight going "heh, you haven't seen my true power level yet" or "wow, Lordran sure is weird haha". My god, why?
Overall, the game basically begs you to play co-op and not give a single shit about lore or story or immersion or any of that. Just "LMAOOOO BROOOO xDDdddDDDD" moments between what I guess is a teen audience. And if you play solo (either of choice or because you just don't have friends that play with you), you get to just trod in almost complete silence (except your character just xDDDdddding on his own of course) through corridors filled with the same enemies, spamming the same abilities. The whole game just relies on other players making the game fun, rather than the game being fun on it's own, no matter with how many people you play. 3/10 overall.