Horrible beyond compare. Not even joking. Play anything else.

Techopolis 3 feels like a deliberate return to classic Minecraft modpacks, just updated with the advantages of modern 1.21 Minecraft. You get smoother performance through Sodium and Java 21, and AE2 benefits from its newer features. Most performance mods still need to be added manually, but the base experience runs well.

A Modern Pack With an Old-School Feel
The “old” feeling mainly comes from the absence of Create. Instead, the pack leans heavily on Mekanism and its own custom multiblocks for almost all processing, which also means that nearly every recipe is changed. The amount of intermediate materials you need naturally pushes you toward building real automation setups instead of relying on early ME autocrafting. The progression is very tier-based—similar to GregTech—where the strongest automation tools don’t appear until far into the pack with Hellish Technium. The AE2 grind exists, but Tom’s Simple Storage makes the early-to-mid game much more manageable.

Weak Points
The pack doesn’t have many major flaws, but a few frustrations stand out.
Thermal Evaporation Plants are used far too often, and you end up constructing them repeatedly, which gets tedious. A larger multiblock that could output around 100 B/t of hot water would solve a lot of this annoyance, since the demand for hot water becomes huge.

The endgame multiblocks are another weak spot. Unlike the impressive, detailed endgame machines you see in something like GTNH, the Techopolis 3 late-game multiblocks look very simple—basically larger versions of the Technium Compressor or the final Technium machine. They function fine, but visually they’re not very exciting.

My Playthrough Experience
I played through the pack on the official server with one friend, which meant I only had nine force-loaded chunks available. That forced me to build compactly, but it wasn’t as restrictive as expected. With careful planning, it’s possible to fit an entire late-game base into a vertical layout that stays within the chunk-loading limit.

Overall
Techopolis 3 is a strong, progression-driven modpack that successfully blends old-school structure with modern Minecraft performance and quality-of-life features. It has a few rough edges, especially with repetitive multiblocks and underwhelming endgame visuals, but the core gameplay loop is engaging, challenging, and rewarding for players who enjoy structured automation-focused progression.

The pack barely feels configured or cohesive. Recipes feel changed just for the sake of it rather than actual balancing, many equivalent items are wildly more or less expensive seemingly at random.
The quest layouts are incredibly disorganized and overstimulating. They're difficult to navigate, and feel like they were designed for zoomed-out aesthetics rather than actually being used and navigated by players. Quest rewards are either completely useless, mildly useful (two or three of a random resource from the mod), or just another of the item you just made, with little rhyme or reason. The quests themselves are often annoyingly specific, such as the AE2 Wireless Terminal quest requiring you to make both a non-crafting wireless terminal and a crafting one, despite being able to create the better crafting terminal without first creating the basic terminal. Quests are also scattered across many chapters, with the same item often completing several nearly-identical quests, with the same nigh-pointless rewards that just fill up your inventory. The quests also teach you less about the mod than the actual guide books, which isn't great for a large kitchen sink pack that will likely be many people's first experience with some mods.
Things are generally poorly configured. FTB Chunks' claims don't allow doors by default, which should be one of the first things that a playtester would discover and change. It really just feels like a few hundred mods thrown together with a bunch of low-effort quests.
The performance is terrible, especially on low-end machines and medium-end servers.
Silent's Gems has been given a smeltery-equivalent, which completely removes the unique aspects of the mod, and turns it into a TiCon ripoff. Many recipes feel like they've been changed just so that they can contribute to the ATM Star, rather than actual balancing reasons.

Overall, it feels like the pack wasn't playtested at all, as most ATM packs do. Poor optimization, poor balancing, and very little configuration.

The modpack has an idea and a goal, which it executes nearly perfectly. An aim to make every mod play its role and achieving exactly that with this pack.

The player can choose their own pace of progression, but if they're unsure, they can always look at the extensive boss list to see, where to go next. Tho the boss list does have a few questionable entries

Combat is refined using the Better Combat mod and a few mods that add a large assortment of weapons, plus several mods having in-built integrations for said combat mod. The combat fits very well into practically any fight.

There's enough to do for any type of player, no matter if you prefer building, exploration, adventure, magic or combat, there's a bit for everyone

As per the modpack's goal, every mod truly feels like a necessary part with their own representation and cross-integration, allowing players to learn something about the featured mods. Although do keep in mind that some mechanics of many mods have been changed.

There are tons of quests to complete, including the Rumors and Village Quests questlines, which embark you on different, well-written stories!

The pack performs well even on lower-end devices, but extensive machines with Create can still tank some frames.

The new golden standard for "Minecraft" Roguelikes

This is a breathtakingly well put together and stable modpack, especially considering it is almost entirely made out of Data Packs, and as the title has said, I really did forget that this is a Minecraft Modpack while playing.

I love every attempt to put rougelike gameplay into Minecraft, and you'll see my reviews on this site back that up, but I genuinely believe this one is special. It is so fully formed in a unique way that others cannot match, not Vault Hunters, not Trepidition, not Roguecraft, not even Minecraft's own 25w14craftmine or the packs to come of it. Even accounting for the deep-pocketed and more mature server dev scene with servers like Telos Realms... Nothing has been able to compare as a total overhaul, this pack truly uses Minecraft as an engine to great effect.

This is not to say it ignores the fact that it is made in Minecraft, it still utilizes the set dressing, visual language, and other shorthands that Minecraft provides well. But without playing it yourself, it's hard to describe just how not-Minecraft this modpack is without that ever feeling like a bad thing. I don't belabor this point to suggest that it should be a stand-alone game, but to commend the team for breaking free of the "uncanny valley" many other attempts at "It's like a game but in Minecraft!" reside in.

Of course, there are a few seams still visible, some menus interact weirdly up close, you have to move around in your hotbar to get to some menu items, there's no voice acting or character speaking noises for dialog, and some menus are navigated with book and quill. But again, unlike the maps, modpacks, and servers you've played before, these don't feel as jarring or restrictive as that all may sound.

This is all to set the stage and preface that throughout the rest of my review, I will be treating this pack as a game, because it succeeds in being the quality of a stand-alone game, and one that would itself earn many played hours from me.

My points of reference

While the game cites Ultrakill as inspiration (and I certainly see it), I'm glad it's not that much like ULTRAKILL.
While I'm a huge fan of 3d shoot 'em up action rougelikes and will never turn down the opportunity to enter a room, bounce off the walls, and shoot hordes of mobs until I get to pick one of three rewards, I often find myself overwhelmed in the most high-octane and fast-paced entries the genre has to offer.
While I've only done about 5 runs (only 2 successfully) I've never felt like I didn't know what was going on or wasn't in control of the game, whether in boss fights or horde rooms.
Even when my screen was so covered in vfx and damage numbers that I couldn't see anything else, or was moving so fast my only ways to navigate were by intentionally running into obstacles I never felt lost.
This game reminds me most of Heart & Slash, Immortal Redneck, Battle Shapers, and in a weird way Deadzone Rogue at least in temperament.

Difficulty and scaling

The difficulty is possibly a little low for some, but it's just right for me.
I don't have a lot of time to play games, and I like that even a successful run is going to be in the range of 30-50 minutes.
I also liked that even my first runs got me pretty far and that there's ample opportunity to get a good and cohesive build early-game, even if you don't get exactly what you want.
Every successful run has me feeling like I'm "broken" and "overpowered" by the time I've made it to the end... of course, all that confidence is dashed away pretty quickly, after the "final" boss fight
That doesn't mean it's without challenge as if you stop pressing your buttons and timing your skills right you will still die quickly, yet not without warning.
Having a relatively limited skill pool and straightforward tech keeps the game from getting overwhelming, even once its cranked up to the extremes, and everything has really good feedback.
While there isn't a tonne of meta-progression in the way I like of permanent skill boosts, there are unlocks that change your per-run progression for the better. These unlock as you unlock higher difficulty levels for your next runs and all feel meaningfully impactful, in addition to unlocking more characters and item unlocks as is typical for this type of game. I've not hit a point where I feel like I just have to grind for a god run, at least not yet.

Builds and replayability.

While there are still some mechanics I don't fully understand or haven't fully unlocked yet, I've enjoyed every character I've tried and could see myself gearing a run towards a focus on any of the three skills for most of the characters.
The characters are all pretty straightforward and understand their role well, and most are surprisingly deep if a little intimidating at first, though thanks to the mostly forgiving difficulty I don't feel like I'm risking wasting my time by trying to learn a new character and have been pleasantly surprised by some of the crazy combos and synergies I was able to accidentally find.
As mentioned above, each run is relatively short yet rewarding even if you don't go all the way. The game does expect you to beat it many times before getting the true ending.
I can easily see myself playing another 30 hours just to scratch the surface of each cool build with each character, and ofc there's a speed run timer if I still wanted to keep playing after that 👀.

The fact I'm even considering that is commendable as in most of the other games I've referenced, and even some of my other all time favorite rougelikes like Rogue Genesia, Into the Necrovale, Megabonk, or Risk of Rain, I really only like playing my favorite character with my favorite build until I perfect it and feel little incentive to try other options (this is why I've never gotten back into even the beloved Balatro).
This game is not like that, and I think that's owed to its relative straightforwardness and simplicity while still offering a variety of content.

Quality of Life & Information availability.

The other contributing factor, however... is probably due to its qol features, good tutorial, and great in-game documentation, stats, and descriptions.
I know I said the rest of this review would ignore the fact that this is a Minecraft modpack, but here I really have to point out how good a job they did at this stuff, not only compared to other Minecraft content but to other full-priced indie and AA games.
Other games need to take note that providing "complex" details to the players who want them is going to be a welcome feature, being able to browse items, and see my stats and equipment in a run is huge.
The hub has just enough room to mess around in without making me waste precious seconds navigating it, not to mention its importance to the story and atmosphere of the game.
The inclusion of a test room with multiple options for dummies is something that really should be a must-have in this genre.

While this may feel like a weird place to talk about this, I also believe how diegetic the game is not only aids the immersive qualities but actually makes it easier to play than if it was a bunch of menus and this is again where I have to talk about Minecraft.
Because this is "vanilla" Minecraft (most of the content is made entirely with datapacks), ATMOS doesn't have the option of fancy menu screens (aside from those literally provided by Fancy Menu, shouts out).
Picking up an item is literally picking up that item from the ground, shopping is also a physical experience, and so is map navigation, cutscenes, menus, almost all of it.
While the devs didn't necessarily have to go this route, I do believe it's born of limitation, like all good ingenuity is, and is better for it. This is one of the main reasons I said earlier that I don't believe this would be better off as a standalone game, because the same qualities that make it better at doing just that than its Minecraft peers also make it a better game period.

Brief warning that I have not played in a long time, but I wanted to give my brief thoughts anyway.
Seeing people push the limits of Minecraft is what I'm all about; it's what inspires me most about this community and what, if anything, I hope to be able to inspire in others.

To my memory, the gameplay was a bit jank, but the author was able to accomplish what very few devs have in a brilliant proof of concept that I hope will inspire more like it. Documenting and leaving open all of this great creative work is very cool, and I really hope to see other "total overhaul" like experiences come from minecraft modding scene as a result.

Even though its main focus is gregtech it still has some other mods(like thaumcraft, botania, witchery, ic2 etc) that work really good with it because of insane amount of custom crafts and interactions

And it runs really good for a pack with 230 mods but it lacks some modern features so it might be not for everyone(has really good music though)

In the fairness of transparency, i am adding that i added two cosmetic things to this modpack, nothing that changes the modpack itself. Just some shaders to fit the atmosphere more and a model change to my character.

I have yet to finish this modpack, but. Liminal industries is awesome. Fair warning now if you are not a fan of create this modpack tends to use it quite a bit. The experience of being of the backrooms is honestly really cool. There isnt really any jumpscare or anything, it just happens to be minecraft but in the original concept of the backrooms mostly. Even without jumpscares playing this modpack alone gives me a little bit of building anxiety just from the environment. There's a ton of different rooms, and once you think youve seen them all you somehow manage to find another room you've yet to run into. Its quite varied. Its so much fun running through the environment and collecting resources to cobble your own.

But... there comes my crux with this modpack. After a bit you do less and less exploration. Eventually you start staying in one area as you can mostly make everything you need there at one point. The exploration sort of dips off and while its still fun it just loses that luster it had at the beginning. I wish there was more exploration to do in the later portion as you just quickly lose any reason to do so. Its not like it isnt fun anymore but i found the uniqueness of the modpack was the environment itself, was the backrooms. I hope that they expand on adding more to explore in the future to give more reason to not just huddle in one area after a bit. Still its fun to be able to turn the anxiety inducing backrooms into a home of your own.

I dont tend to finish minecraft modpacks not for lack of liking them, but more so attention span. Deceasedcraft is one of the few i finished and i had a blast pretty much the entire time playing it. The experience is very much different from normal minecraft. You can find most of what you need just looting and ransacking and the movement makes it fun to bounce your way through cities. Minecraft looter with guns works surprisingly well. There isnt a super extensive questbook but there doesnt need to be.

The only issue i really have with it is the wastelands. The main building you have to find in there has an absurd number of enemies spawning, with block breaking capabilities and going through that entire building my FPS was crippled. Powerpoint levels of frame rate. I also found the (spoilers ahead) dimension at the end very lacking and just uninteresting, so it just kind of dropped the ball at the end of the modpack. However it was still fun, it just wasn't as captivating as the beginning. Overall a super fun modpack to play, even more so with friends!

Multiple chapters that with duplicate work; for example craft a Create Press or Mixer then in another chapter a little ways in I need to submit the same items.