For anyone wondering how to play, I think I got it more or less figured out. Honestly not too sure myself though, so feel free to correct me if I'm wrong.
At the top of the screen, the number after "player" and "opponent" are your health and opponent's health respectively. You win if you deplete your opponent's health, and lose if your health is depleted.
The number on the top left of each card is the mana cost. Bottom left is attack, bottom right is defense.
Some cards also have an "!" icon after the attack or defense numbers, which is an additional effect that occurs whenever they are used for attacking or defending respectively. Mouse over the icon to check the effect.
Not sure how to trigger the effects at the top or bottom though, or what are "build points"? Also, mouseover for tooltips doesn't seem to work when checking defending cards.
The stack of cards on the left is your deck, the one of the right is your discard pile.
Drag cards to the left/red section to have them attack, the middle/yellow section to send them home and increase your max mana for the rest of the game (effective starting from your next turn), or the right/blue section to have them defend. Attacking or defending requires mana, sacrificing does not.
Cards that attack or are sent home get discarded after the turn, while cards that defend remain until they are defeated. You can see defending cards from previous rounds by clicking the button that says just that; the ones on the left are yours, while the ones on the right are your opponent's.
After ending your turn, your attackers attack the opponent's defending cards and reduce their remaining defense, directly attacking their health instead if they have no defenders. The "attack" value is the total amount of damage they can deal, either to defenders or your opponent, before they are discarded; so a card with high attack can take out multiple cards with low defense. Then your opponent does the same.
As for actually winning, a couple of strategies I found were:
- Human: They have a Priestess (of victory) card that auto wins the game when used to attack or defend, provided you can pay the 10 mana cost. Stall and defend until you can amass the mana to play it. With the exception of Crane who has 0 defense, I'd use any other card for defense, even if they aren't good at it, and send home the Cranes. Since defending cards don't get discarded or returned to the deck until their defeat, doing so allows me to thin my deck to 2 Cranes and 1 Priestess, guaranteeing I'll always draw Priestess (unless one of my defenders die)
- Elves of the Blue Library: Seems like most of their cards have effects when attacking, so the best strategy I found was playing as many attackers as I could while sending home whatever I couldn't afford to play.
- The Battle Dogs: Their deck has two Media acies cards, which scale based on how many cards you've sent home, and two Postrema acies cards, which gain extra defense every round. Defend with the Postrema acies, attack with the Media acies, and send everything else home (even after reaching max mana)
Overall, pretty fun once you get the hang of it, and great art, too. Though I do agree that it needs more explanations; there's still a few things I don't quite understand.
Couple of bugs and typos: "opponent" in the top right is misspelled, and some tooltips say "%d" instead of whatever the value is supposed to be.