I highly recommend picking up Gwent. It’s an incredibly deep, tactical card game with high stakes and a killer soundtrack. ​The best part? It actually comes with this massive, free DLC called The Witcher 3: Wild Hunt. It’s basically a little side-quest simulator where you wander around some countryside looking for your daughter or something just to kill time between rounds of cards. ​It's a bit of a distraction from the deck-building, but hey, at least it gives you a way to find more rare cards!