Let me start off by saying that this pack is not for everyone. If you're looking for intense boss fights, dungeon exploration, and looting, then don't bother. For automation enthusiasts though, this is a wonderful experience!

what the pack is about

This pack revolves around the idea of accessing new dimensions with each stage of progression, and extending your automation capabilities with resources obtained from said dimensions. A concept that feels fresh, and is very well executed!
There's also an underlying story. It's not super complex, but it's a fun addition, and it ties the elements of progression together.

design choices

The pack is minimalist by design - there are no unnecessary mods, and a lot of recipes have been disabled to force players to approach problems in creative ways. A great example is how Botania's mana generation was completely redesigned for the purpose of this pack. A bonus of this approach is that the pack runs very smoothly. I've built some questionably efficient setups, loaded many chunks, and had no problems with lag or TPS.
Another thing this pack does really well: usually when you get started with a mod, you're forced to use tedious or inefficient methods to obtain resources related to it. What's great is that later on, you usually get access to a far more efficient method of obtaining those resources. It's a pattern throughout the whole pack, and it feels rewarding every time.
Playing this pack feels very much like a curated experience, and you can see the effort put into its development at every step of the way, right up to the end.
What really surprised me was the receptiveness to feedback from the modpack author. Every issue I've had with the pack, or idea I've proposed, has at least been considered by the author. I don't think I've ever encountered such a level of engagement with the community before.

issues

The only issue I have with this pack is the endgame (and this is the reason for 4.5, not 5, stars). It just felt slow and grindy. The pace really drops in the last chapter of the pack, and if you didn't anticipate the huge need to scale up, you might be forced to AFK. That being said, there is nothing in the endgame that "just appears out of nowhere." What I mean by that is: for every resource you need in large quantities at the end, you should already have at least a basic setup for it. There are no sudden new mods you need to interact with - you just need more of everything you've already been doing, and I think that's a great approach.

One final note: this is a 1.12.2 modpack, so if you're like me, you might miss some features from mods in newer Minecraft versions (especially modern AE2 features).

I found this modpack looking for an expert-ish modpack with overhauled progression and crafts that could be completed in around 100 hours. This is a story-based pack that will take you through five custom simulations where you will slowly unlock more and more technology/magic and the ultimate goal will be to automate vast quantities of many different and unique resources. You will find a lot of automation and logistical challenges in this modpack, such as an entirely reworked Botania mana generating system. Many custom Modular Machinery multiblocks are in this pack as well. Many of these multiblocks provide new crafts to progress your game state, but some, like the Slate Ossuary, make creating blood magic slates much easier. The author of the modpack, InterationFunk, also put a great deal of thought into decluttering the modpack. What I mean by this is you won't find your inventory full of a thousand different fauna or other resources that you say, "Oh let me just put this in the trash chest, maybe I will need it later." All in all, this modpack offers a very clean experience that can be reasonably completed in under 150 hours while also providing an awesome challenge.

I highly recommend this modpack to anybody looking for a shorter, automation heavy modpack.

Cryogenic Simulation by IterationFunk, is a master class in what a modpack should be. If I were to define what makes a good modpack it would come down to three main criteria. A strong central theme, a well curated mod list, and well balanced progression. But what makes for a great modpack? Innovative ideas, structured progression, and breaking the mold for what makes a standard minecraft playthrough different.
We start our journey in a void world, nothing but a monitor with some lore and broken portals. This central hub is the base for our exploration of the different simulations that the pack asks us to beat. Each simulation provides a different challenge and progression that must be accomplished before you can move on to the next. For example, in the first simulation your main goal will be to produce steel and that same steel production will follow you throughout the remainder of the playthrough as steel becomes a key resource that will be used in crafting more advanced materials. The guidebook, while a bit nebulous at times, provides for structured support on how you are meant to be progressing and giving out specific tasks and goals to accomplish in order to finish that specific simulation challenge.
The simulations is where this pack shines, each simulation has its own theme and set of challenges that test you in different ways. Generally I have found that exploration and combat in modpacks is either undertuned making it unnecessary or completely broken making levels of progression get completely skipped. Cryogenic Simulation managed to make exploration challenging and rewarding without being overpowered. Certain key resources are hidden from the player, in simulation 1 this is in the form of experience books, in simulation 2 this is sooty marble in the dimensions dungeons, and in 3 its the certuz quarts hidden underneath the high bedrock layer. This really shines in simulation 2 and 3, while necessary in simulation 1 exploration only serves to locate key resources like Clay. They could have taken the easy way out and just made all the ores/resources you need found underground in caves and have you go mining but instead Simulation 2 has dungeons spread across the land and your reward for conquering each dungeon is a slew of resources that you can use in that worlds progression which saves a lot of time over doing tedious crafting and locating raw resources. Simulation 3 has what I would call Battle Towers for being so tall and dangerous but the tower itself can be torn down for usable resources and inside holds more key resources for that simulations progression. You're never finding some random late-game items; it's always loot tailored to that specific simulation's demands and are easy enough to find to be useful.
Now lets talk the mid-late game, After unlocking simulation 3 and getting access to Applied Energistics the modpack slows down like a car in gridlock traffic. Its at this time when you have to take a huge stepback and start building out centralized storage and passive automation of many key resources in order to set yourself up for the late-game. Automated quarries and simple mob farms are going to be key here because of how crafting and automation heavy the pack is going to become. Now unlike alot of other modpacks Cryogenic Simulation warns you in advance that its going to start getting automation heavy and outlines a number of key resources that you should automate now to save you time later on. I liked this alot because usually what ends up happening in the late game comes across like a suckerpunch to the head. Many modpacks dont provide a good ladder for the grind and just kinda drop you into it. If youve ever played UniversIO you know what I'm talking about. Its as if the author didnt know how to resolve the end of their pack and simply wanted to pad the gametime by introducing a massive resource grind. Cryogenic Simulation does the opposite, it lets you know that the grind is coming and gives you cheap tools to automate it. AE2 items are very cheap compared to other packs which makes building out automation more about the puzzle and less about the grind. Now the final end-game grind to finish out the pack does have some super massive resource sinks taking millions of items but even that grind wasnt too bad because you are given extremely powerful ways to generate raw resources. The World Wyrms while flavorful present a unique challenge in powering them but the reward is resource post-scarcity. I would say that the kinda out of place Crop item grind was a bit of a slog as you need 9 different farm crops in the amounts of tens of thousands in order to finish one of the final items but apart from that every other crafting challenge up to that point felt rewarding to accomplish.

In addition, what I enjoyed the most out of this modpack is the variety of crafting puzzles that were presented. While resources are cheap, the challenge is setting up passive automation to produce the final outputs. Hyper Nutritious Wyrm milk for instance, took multiple resources processed in different ways in order to produce it. All the input items by that point are extremely cheap but the challenge was feeding them into the system in efficient ways. The Thermoelectric generator is a good one as well, an early multiblock machine that produces massive amounts of energy that will get you to the end-game before nuclear options. Keeping it stocked full of fuel provides a neat challenge early on before you can easily produce its fuels via simulation chambers and automated mining. The changes to Botania were probably my favorite, usually Early game botania is spam endoflames to make mana until you can unlock the better flowers later on. But by removing that entirely and replacing it with The Primal mana resource, producing Botania’s end-game materials didnt feel like a massive slog where you are always waiting around for more mana.
At a playtime of around 75 Hours to complete, assuming an advanced understanding of modded minecraft, Cryogenic Simulation is a great modpack that I would recommend to people looking to dip their feet into modded minecraft. It makes tech mods very approachable while explaining the key insights needed in setting up automation chains and general resource management. It doesnt rely on you already being an expert level player. This is something that quote unquote Expert Modpacks always seem to miss at least for me, an expert level modpack should mean that there will be crafting and automation challenges to solve and not that crafting bread will first take 30 steps and 15 different machines.