Challenge by: reminiscent-afterthought
Because there's a card game, so there must be a challenge for it, right?
The goal is to unlock all the character decks, one deck at a time. Each time you reach 15 points for a deck, a new deck will open up. The ultimate goal goal is to have one fic written for each card.
You don't have to include the card. Rather, each card will give you a certain task. Completing that task earns you the card (aka some points). Doing certain cards in sequence allows you to earn more points. But you have to have the cards in your hand to be able to play them in that order XD
Well, choose isn't quite the right word. This is a card game, so part of it is on luck. You get a draw of five cards each time. To do this, use a random generator from 1 to the last numbered card on the deck you're working on, then generate five numbers. You pick one of those to do your task on, and then you get a new card to replace the one you've used (so back to a hand of five) and pick out of those for your second fic. Reroll if you get a repeat.
That way, there's a little bit of choice, but also a little bit of luck. Tasks vary, and the points assigned are graded by their length and complexity.
Start with Ruuko's deck, and work your way through. Enjoy!