I have good news for you.
First off, the game is 100% solo'able. There's nothing in the game that requires multiplayer (except maybe unlocking a trait or two that are used for multiplayer). You can see all the content, do all the dungeons, and kill all the bosses by yourself, 100% guaranteed.
Secondly, to answer your first question last, the game actually isn't "too random" IMO... but of course, that's just my opinion, so let me explain:
As you've probably seen in some videos, the campaign is generated with a set of guidelines. These are the rules that determine your route through the game. Think of it like this...
Imagine taking a road trip from California (San Francisco) to Texas (Austin). The route planned says "you must drive south, pass through Arizona, then New Mexico, and then Texas". Those are the basic guidelines.
Then the engine says "you must stop at 4 gas stations in each state, and eat at 2 diners... one for breakfast, one for dinner".
That's basically it.
We can guarantee you will see certain story moments because we know you will go from CA to AZ to NM to TX, but we don't know what gas stations you will stop at (we've build way more than 4) and we don't know what diners you will eat at (we've build way more than two). Along the way, you might veer off on a side road, or go to a third diner, or stop at a different gas station, but that's up to you. In fact, they may appear, they may not, but the original guidelines will ensure that at least the base amount will spawn. Which ones actually spawn though, are random.
So, now imagine CA is Earth, AZ is Wasteland, NM is Yaesha, TX is Swamp. Imagine those gas stations could be Texaco, or Shell, or Exxon, or BP, or Chevron, or Marathon, or Tesoro, or Rotten Robbie, or Valero, or Parker's. Each of them are biome themed and offer different stuff... and as mentioned, the engine only ensures you go to 4 of them in each state.
Now imagine those diners are TGIF or Applebees (LOL) or Cheesecake Factory or Red Robin or Black Angus or Bucca di Beppo or Claim Jumpers. Again, these "diners" would all be biome themed and have unique... "dishes" to serve.
When Chevron spawns on your route, you know that you can get X from the gift store. When Valero spawns, you can get Y. When Marathon spawns, you can get Z.
Same for the diners... except with bigger and better rewards.
OK, this analogy got out of hand real quick. The point is...
We have a set of guidelines and... now I'm hungry.
[F]
The idea of this system is so that a) you never see the same thing twice in a single play-through, b) each run/campaign is laid out differently BUT it has a set of rails, so to speak, to keep you heading to the final destination, and c) when you re-roll the campaign (or adventure more) you'll never get the same route.
Also, you literally cannot see and get everything by playing through the game once. It's impossible... because every world has multiple world bosses and you only fight one each run (per biome), every Biome has multiple mini-bosses which work similarly. Every mini-boss has random modifiers. Every area has different world drops as well... BUT, as I said, there are a set of guidelines.
You will know that you can eventually get everything in a biome because multiple elements are tied to "events" that spawn in the world. We may have 10 world-drop items that can appear from exploration. As you pick up 1, there's now 9 that can spawn in the same amount of event spots. Once you get 2, now there are 8. The game rewards playing again and again.
Plus, Adventure Mode will allow you to roll a single biome with no story elements and only part of the aforementioned "route". "I JUST WANNA PLAY ARIZONA OVER AND OVER!" Cool, do it!
Anyway, sorry for the ridiculous analogy. I'll see myself out.
