The Simulated Universe is one of the first features the game introduces to the player. Herta wants data on the Aeons, and so built a device that can simulate the universe. When the player accepts the invitation of the Astral Express, Herta urges them to use the device and explore the simulation.
To facilitate the meeting with Aeons and get her data, Herta puts the Trailblazer in the shoes of Akivili, the disappeared Aeon of the Trailblaze. It worked, and the player meets Fuli, Qlipoth, and more throughout their universe exploration.
Still, World 1 and 2 let you dip your toes in the mechanic before diving headfirst.
World 1 Guide
There's little to say because Herta guides you throughout the run. Your units are also Trial characters, the three you start with (Trailblazer, March 7th, and Dan Heng). You'll only be able to use the Path of Remembrance or Preservation and meet the other Aeons as you explore more worlds.
World 1 is the shortest, with only 7 rooms/domains, one elite, and one boss. It is a sampler of what you can encounter in other worlds of the Simulated Universe.
You'll learn about the different domains from encounters, occurrences, and respite. There's also the Blessings system that helps you throughout the dungeon. As mentioned, you encounter Aeons in your explorations, which open up new Paths.
This will show you the basics of the Simulated Universe, and what you learn here will be built upon in future worlds.
World 2 Guide
World 2 is more like World 3 and beyond than the sampler that World 1 was. It has 13 rooms like the other worlds, and two elite enemies and the boss. However, one thing that sets it apart from Worlds 3-6 is the lack of Immersion Rewards.
This World won't give you Planar Ornaments and does not have difficulties like the ones after it. Still, it gives you an idea of how those will go, with two elite enemies and the boss at the end. It'll teach you how to know if you're going to survive the run or not. There's also when to choose Occurrence or combat domains and what you can expect from future runs.
It's basically a practice run, and though it doesn't have replay value, doing it is still rewarding. You'll get Herta Eidolons, some Stellar Jades, and Trailblaze EXP.
Since it's like the ones you farm Planar Ornaments with, you can experiment with different Paths (currently available) and team compositions. Well, it will be better to do this in the other worlds once they're open.
A Summary
World 1 and 2 of the Simulated Universe might be practice runs, but they're good introductions to the feature. The Worlds after these would increase the mechanics' complexity by adding more Paths, so this is the last chance to experience a simpler version of the Simulated Universe.
However, the more complicated the mechanics, the better the rewards. The things you get for completing World 3-6 is worth the practice from World 1 and 2. You can only get Planar Ornaments or first-time completion rewards if you take World 2 seriously and figure out strategies.
With Relics' reliance on RNG, you'll want to keep doing Worlds 3-6 to farm Planar Ornaments. You need to learn how to explore and at least get to the boss room to grind for what you need.
Have Fun Playing the Simulated Universe!
The Simulated Universe is a gift that keeps giving, though you will only go far if you do the Worlds in order. They introduce many mechanics and Paths, and the game keeps you from doing it out of order (at least for the first time). Afterward, you can choose whichever World to play.
Still, the difficulty increases as you progress, meaning you must also get more potent and adjust your strategies depending on the boss. Without it, you won't always have the potential to claim Immersion Rewards, as it is only available after defeating elite enemies or bosses. The latter even provides two claim instances. Defeating only the elites will give you half of your potential rewards.
You're better off learning the basics and in and outs during your runs of Worlds 1 & 2, so don't discount it. Besides the Immersion and first-clear rewards, there's also the shop containing Rail Passes and 5-star Light Cones.
