I noticed that the first expansion is the start of the "Dunwich Cycle". Now, the only LCG I've played before is Conquest (and a little bit of LotR) and I generally just buy random decks and mix them all together. But, AH:tCG is a campaign game so I'm assuming that each of the scenarios from the Dunwich Cycle are tied together in one long campaign.

My question is, how can this work? Do I have to buy all the Mythos Packs and play them in order? If not, then how can these packs be part of the same story-based campaign when they can't assume that any but the first two scenarios have been played. And how does this Rougarou scenario fit into all this.

I guess my main issue is that there doesn't seem to be any sort of balancing mechanic where the scenario get's tougher based on the experience of the investigators. With a fixed scenario campaign, such as Imperial Assault, you can make the later scenarios tougher because you know that the characters have improved before playing it. But in this game, the scenarios are sold separately so they can't assume a specific power level.

Also, are the two announced Dunwich Mythos Packs (the Museum and train one) the complete Dunwich Legacy campaign, or will more be added?

I think the power level is balanced in your deck. If you play from the beginning you'll have more XP, sure, and get good cards.. but you'll also be adding traumas and potentially more weaknesses to your deck. I'm sure there will still be a bit of a power curve, where some scenarios will always be harder than other ones, and it would make sense to escalate over a cycle, but I think the gameplay balances it all out. In fact, if you look at the rules for playing a standalone scenario, it suggests that you add weaknesses based on the XP you add to your deck, showing that you wrack up as much pain as you do power.

Curse of the Rougarou is a standalone scenario, you can spend 1 XP in the campaign to play it as a sidequest, or you can just throw together new investigator decks and play it. It won't tie into any story.

The two mythos packs revealed are part of the Dunwich Legacy, and there will be four more. Overall a cycle will have one deluxe box and six mythos packs.

To go with the eight scenarios being one story, I can see the 2 Dunwich Legacy scenarios are you working with Armitage to research whatever happened in Dunwich, which leads to going to the Museum as the first pack, and then having a place to go, so you get on the Train in the second pack to go somewhere. I see the last four packs taking place in Dunwich, or somewhere else, to continue the narrative. Obviously without playing the Dunwich Legacy, I'm only giving my opinion, but I would urge to play them in order. Going back to the standalone rules, it tells you to start at the beginning of the campaign and read through the guide, choosing the outcome you wish, but taking the effects of it. So if you play scenario 6 (of 8) first, you'll basically read the story of 1-5 before you play. This would take away from playing those scenarios, at least to me. Granted, you can only have that surprise of a scenario once, but personally I'd like to have it. Now I did not play the LotR LCG, so I don't know if the deluxe boxes campaign guide has all 8 scenarios in it, but I almost feel that this game will have it based on what I have read. I could see that happening as I'm sure the full cycle is already developed, even if they're tweaking a few card mechanics for later in the set, but again, I have no clue.

I hope the boxed set campaign guide has all eight scenarios in it or at least a Campaign Log that lists them all. The game store display gets confusing fast with all the packs of these LCGs.

I wish that trauma was represented by some sort of cards similar to Weakness cards instead of just a point of damage. That way you'd actually experience your character going insane as you'd be constantly drawing these weird phobia/maddness cards during play.

SuperMarino pretty much has it right. The only difference in the release schedule for Arkham compared to other LCGS, is that they are starting with the deluxe rather then building up to it. This will probably be to inject more cards into the card pool. In LoTR each scenario came with its own pamphlet and encounter deck construction guide so I would imagine they would keep it the same to reduce spoilers of people reading the end of the campaign before its even released if it were all released in the deluxe. I would also imagine they will create new campaign PDFs to follow along with because they will be a lot longer then the 3 scenarios we have now as well as more spread out.

They pretty much expect you to buy each mythos pack as its released and play it and then wait for the next one to continue the story.

I wish that trauma was represented by some sort of cards similar to Weakness cards instead of just a point of damage. That way you'd actually experience your character going insane as you'd be constantly drawing these weird phobia/maddness cards during play.

I agree to some extent, after playing Scenario 1 with Roland, he took a mental trauma, which really shaped how I upgraded and played over the other two scenarios, always trying to mitigate having only 4 Horror, which is a pretty tough thing to do. So I like how the game forced me to deal with his trauma. I just wish there was something a little more mechanically satisfying than just starting down a point. Of course, there will be other weakness cards and stuff added throughout the campaigns that will make us happy that trauma is only being down a point, so I guess I'll be okay with it for now!

My question is, how can this work? Do I have to buy all the Mythos Packs and play them in order?

Yes

If there is no trauma points just weaknesses, characters that are mainly about drawing cards could be considered weaker. Also there would be weaker impact of drawing weakness if you get 10 of them in the deck. It's good that developers got both options, trauma and weaknesses to show weariness of mind and body of the person who is investigating the eldritch things. That way it could be used in grim harmony that don't destroy balance of the game.

I think the power level is balanced in your deck. If you play from the beginning you'll have more XP, sure, and get good cards.. but you'll also be adding traumas and potentially more weaknesses to your deck. I'm sure there will still be a bit of a power curve, where some scenarios will always be harder than other ones, and it would make sense to escalate over a cycle, but I think the gameplay balances it all out. In fact, if you look at the rules for playing a standalone scenario, it suggests that you add weaknesses based on the XP you add to your deck, showing that you wrack up as much pain as you do power.

In addition to your deck balancing itself with traumas and weaknesses, they can also use the campaign system to make certain things more difficult if you've played the earlier scenarios. This is the case, intentionally or otherwise, in the core box:

The official rules for standalone scenarios require you to go back through the campaign log and set up the resolutions as appropriate.

It says to choose resolutions and apply the results, but many results are conditions that cannot be determined.

The rules are also very generous in allowing players to choose any resolution and apply any results they wish.

The whole standalone rule is a bit of a kludge, IMO, but even with the strictest possible read of RAW, only one of the three outcomes I noted in spoilers is altered (the GP).

It is meant to be done like a choose your own adventure book.

So if you were doing scenario 2 as a stand alone, you'd essentially ask yourself "Did I kill the Ghoul Priest?" and "Did I burn my house down?". You could also say, "I stayed in the house and died to a ghoul infestation".

Essentially any choice that could change the setup of the scenario you plan to play standalone you get to pick and choose what you want. So if you're doing Scenario 3 as a standalone, you'd walk through 1 & 2 making choices, and taking the consequences.

You can set it up where you're in a great place, or set it up where you're in a terrible place, the choice is up to you.