Summary: The game is quite good, but it's not perfect. There are minor hints at mobile heritage, but nothing that would stop anyone who might like a computerized card game from having plenty of fun.
Progress Disclosure: I finished the game and have every achievement. I didn't collect every card. That took about 14 hours. It could probably be done in 8-10 hours by someone hurrying.
Updates: It's over 2 months later, and this game is still getting free content additions.
The mechanics have clearly received attention and tuning; the basics work nicely on their own, and as more abilities are introduced they interact in interesting but not convoluted ways. The interface in general is good; however, it is full of tiny delays for animations and pointless confirmations of non-permanent actions. Combat animations can be set to anywhere between 100% and 200% speed in the options, at least.
The tutorial was good, even having heard and read nothing about the game except the store description before playing. The difficulty hasn't sharply spiked or stayed tutorial easy since; the AI can be observed getting steadily more competent in addition to having better cards. Most games are semi-close wins, and the occasional enemy provokes a new deck style. I have a win ratio around 5, and I doubt that's exceptional.
Deck size is allowed to vary between 25-40 and failing to draw causes damage, so milling is a somewhat viable strategy with the right cards.
There's an deterministic, seemingly associative 2-input alchemy system. The vast majority of combinations are disallowed, and this is indicated by dimming incompatible cards; there's still a pretty large space of recipes, though. A little experimentation produced some deck-worthy but not ridiculous cards. As an example, two Pancakes gives a pretty good milling card. I didn't find a guide, so I'll warn that in my experience combining a alchemy-created card and one of the ingredients used to craft it is allowed but just gets the created back, effectively throwing a card away.
There are 6 icon-identified deck slots; a card can be used in multiple decks. The deck building interface is passable if imperfect; it lacks bulk management options, and the sorting options are deficient. It could use a tweak to show more cards on a PC screen. Cards used in decks are hidden on store and alchemy menus (for good reason).
The art style is pleasant. The dialogue is mildly humorous overall and better in parts; the optional dialogues are pretty extensive, as well.
The achievements look to be quite doable, so it would probably be good for 100%ers. The non-trivial ones (10+ attack and 9 combo) are easy enough to manage once you have a 6+ arrow card and deliberately try.
As described, there are no hidden in-game currency, card, or booster purchases.
Accessibility: The game is fully turn-based with no time pressure ever. The interface doesn't require great precision, but it does require dragging. The interface is fully mouse-driven, except optionally entering your name. There are no vital sound-only cues. No lines are voiced; all dialogue is presented in text. Nothing relies purely on color for identification. As a non-expert, I see no problems.
Posted: February 14th, 2014