Thanks for the feedback Auer!
The game does unfortunately lean a bit on mechanics established by other deck building games, making it hard to know how much needs explaining. I lean towards not over tutorializing games as I feel like players naturally discovering mechanics and interactions within the game themselves is part of the fun of gaming.
Because of this I'm actually glad that the lack of over explained end-goal led you to work towards the end goal naturally (don't get overrun by cards from the rift deck). There is a help section available in the corner of the game screen that will explain some of the verbs / actions the cards perform, as well as high level objective information for those who want it however.
As for the discard pile, this could've been more clearly indicated to the player through animations on my part.
When your deck runs out, the discard pile is shuffled and made into your new deck. This means cards you buy make their way into you deck / hand after that re-shuffle (the base deck is only 2 hands long [12 cards]). This mechanic is to have the player think more about what cards they will need going forward, not just what they need right now, since this game can last 40+ turns.