Computer games, often with friends. I really love complex games with lots of secrets and tricks to master. I love Dota 2 with my buddies because it feels good for our organization and our ability to help one another to win out over people who might be better players individually. I've also been addicted (again) to Dark Souls because it is so winding and labyrinthine. It's hard at first but becomes easy once you master the mechanics - the part that keeps me coming back is the story though. It never tells you anything outright, you have to search for answers, and put everything together like a puzzle. The gameplay is challenging, sure, but the story? The story is the hard part. That's the kind of fun I like to have.
I tried a PC port of Dark Souls but I couldn't get past the horrible controls. Do you play on PC or console? If you like action RPGs you might want to try Path of Exile.
PC. I've been using a Playstation 3 controller with motionInJoy emulating a 360 controller. With that it works superbly, if you possibly can use a controller I'd highly recommend it. Also, in case you don't know, DSFix is a great mod that lets the game's graphics live up to their full potential on PC. Between those two I find the port very enjoyable! I've heard good things about Path of Exile, I'll take a closer look though! The customization options seem really deep, which is always interesting.