The game sees you choosing one of three characters as you fight your way, floor-by-floor through individual enemies, sub-bosses, and level bosses. You collect defensive, power, and attack cards as you continue your fight as well as artifacts that can have powerful impacts on your play style. Each "run" will likely end in your death and you will start all over again with the default set of cards.
It's considered somewhat of a Rogue-like in that you gain "some" abilities that carry over from run to run. But it's not the composition of your deck, but rather what cards and artifacts are available (each occurs randomly) based upon your persistent level.
I've found it to be very difficult, but whimsical and fun. There are different ways to play the characters from defensive to offensive and anywhere in between.
My username on Steam is the same as on here if you care to add a friend to compare you performance on "daily runs" etc.