It's designed by Richard Garfield. That is to say, it's designed really well.
Feels really fresh compared to a normal CCG. The game contains creature cards that can be played and fight; and there is tapping and untapping, but those are the only similarities with MTG. Most cards don't cost anything, but the game does not degenerate into Yugioh; the win condition is not combat; each turn you only get to do things with a third of your deck (and which third is an exciting strategic choice), the combat is radically different, the stats are radically different, the economy is radically different, etc etc.
You don't get to collect cards or build decks, but it's a feature and not a bug. Everyone gets an entirely unique procedurally generated deck! And instead of obvious prevailing archetypes, you play with what the god sends you. (But, because the commons aren't legally required to be weak, dull, and uninteresting here, the games are still interesting and unique.)
Also, some cards have simply delightful theming. Curiosity is a spell which kills all scientist creatures on the board. There's a card named Yo Mama Mastery.
And online, there's a fan-made app where you can play it entirely free. With any decks you wish. No microstransactions or whatever.

Since the resources for the game are surprisingly hard to find, here are:
https://www.keyforgegame.com - the official site
https://thecrucible.online - a free app to play it online
https://archonarcana.com - a good wiki with a good card gallery
http://decksofkeyforge.com - search engine and evaluator for decks

Yeah, played a few games after picking up a precon from the first set a few months back. I've enjoyed every game I've played; only gripe is that the power level between decks (which you can't modify) often seems to dictate the winner.