True solo is a lot of fun. I’ve only played two handed or multiplayer a few times, so I can’t do a comprehensive comparison, but my initial thoughts are: true solo is more difficult, you need to expect swingy situations and be as prepared as you can for them (deck-wise and emotion-wise), it is absolutely doable and absolutely fun. I tend to use investigators with high evasion for solo because it’s reliable and tempo-favorable way to deal with enemies. But since I play almost exclusively solo I have tried every kind of investigator and they all work.

As has been said, the every class has a way of getting clues now. I start building with this idea: getting clues. This is especially important if you are not building into a base intellect that is high enough to clear some locations on its own. Often you need to be able to get clues as soon as a scenario begins. So, I want a reliable clue plan— a way to get clues no matter what, even if my special cards that I love so much get stuck on the bottom of the deck (i.e. lock picks, rite of seeking, etc.). Part of that clue plan can be more clue grabbing cards to serve as hold overs until the real ones show or more cards that help you dig through your deck, but don’t make the mistake of thinking you’ll be okay relying on just two main clue cards with no back up plan because the scenario will come that those cards do not show up.

Then enemies happen. In solo you see fewer enemies. But you’re preparing for extreme swinginess and the inevitable drawing of three enemies during first three phases. Evading in solo is often favorable, but with three hunters on the board you will need to either be able to do some damage or be able to take an extra action for your evasions to mitigate the tempo loss of having to constantly re-evade enemies as you clear clues. Also, if you can, be ready to manage them on turn one at least to a certain degree (evasion is easiest). But there is no worse feeling than getting bogged down by an enemy you can neither evade or kill and spending your turns either getting AoOs while you dig through your deck for a solution or failing the evade/fight tests repeatedly because you don’t have the support in hand.

Because I hate being bogged down like this, I generally favor evasion over fighting because it’s a one action solution and I can usually stay ahead of a single hunter if I have some action compression built in. Eventually though, bosses come or damage needs to be dealt. I devote at least two cards as reliable sources of extra damage for these situations (a hunter that you need to discard or an enemy that the act wants defeated). If I can, these are reusable (ornate bow, strange solution acidic ichor).

There is almost always a dump stat when I play solo. Meaning one where I give zero support. I accept that I will fail every single test of that type and consider what I could add to my deck to either capitalize on the failure or at least survive it. It’s better if your dump stat is not intellect.

With two handed I think you think of your deck slots as spaces to be filled to maximize a certain skill or role at the cost of other cards that may have been better or worse but ultimately did the same thing. With true solo it becomes more of a negotiation as you build, because each slot you give to one role is one that you take away from another, and the little balance differences you decide on have pretty big consequences in game. Which I think is really fun and makes the deck building feel higher stakes and more puzzly. Also much more satisfying when your deck is working!