What kind of deck building game is this?

[FroBodine]

Is it like "Slay the Spire" where you collect cards as you go, and start with a very small fixed deck? Or is it like Magic: The Gathering where you have to build a full 60 card deck before you can even play?

[Ruanek]

It's closer to games like Slay the Spire or Monster Train. Each hero starts with a deck of 15 cards, and after every fight you can add a random selection of cards (or get gems instead).

[judcohan]

Just to add, the gems can be used (in towns) to create specific cards if you want stuff that you haven't found randomly.

[Shneekey]

Yea, each character has their own starter deck, but you can curate your decks to an extent at the towns at the beginning of each act. The degree to which you can curate your decks is based in part on your meta progression, as it gets significantly easier with certain town unlocks, and starting with some gems from your previous run.

[[EOGa] Shade]

"Deck building" are games where you build your deck as part of playing the game.
MTG is considered a trading card game. (It was the first one)
Dominion was the first deck building game. Most deck building games are structured somewhat on the concepts it established.
(Sorry for this rant.)

I can say that this game has 4 "classes", and they have different pools of cards available to them.

[malogoss]

Closer to Slay the Spire, with differences.
Imagine a StS game, where you pick 4 characters at the start to form a group, each from whatever class you want. In AtO classes are also divided in kind of "sub classes" too. Each starts with a specific 15 card deck, that's the minimum size. As in StS, you'll find cards after fights, each character is offered cards, each can either pick one OR get some gems.

Those gems can be later used to craft specific cards. In StS terms, it would be like being able to spend 300 gold when you enter act 3 to craft a rare card of your choice, for example.

Another thing. Say you complete a full StS run in 50 minutes. In AtO that would be more like a 2h30 to 3h30 run, rough approximation. I like to take my time with new games, I remember my first (edit: completed) runs being over 5 hours long. But it's more like a nice long journey. Never fell asleep in those 5 hours.

So if you want a game similar to MTG, then skip this one. If you want something closer to StS, that will make you feel like going through a story, where your characters will level during a run and gain character specific abilities, where you will manage multiple decks or play multiplayer with friends, then yes, AtO could be something you'll like, for sure.

[LurkerintheVoid]

One this to note, unlike Slay the Spire there is some progress that carries over, either into the next run or all future runs. You characters gain perks which do make them more powerful. You also can unlock upgrades to the towns at the start of each chapter.

The game is difficult at first and you likely won't complete your first few runs until you have some upgrades (although I'm sure people will post all about how it is possible). I think my first run ended at the first boss but with each run I got upgrades and was able to make more progress. That being said, it seems like they have made the game more difficult over time and I see at least some people commenting on how much grinding is needed in at the beginning. I haven't bothered to do a fresh run with nothing to test it as I personally don't feel compelled to test it so I can't really say.