Dark Souls is a refreshing challenge that I've been slowly chipping away when I get the chance. I love the throwback feel of the NES difficulty and the exaggerated level design. Its a feeling I got when I first played Ocarina of Time and I thought I never get a similar feeling back. The beauty of the game is that much of it was planned really well. The lore is incredibly deep despite the very little information given and even the environment tells stories in neat ways (some corpses you find are dead in certain places for a reason). Now the best part is each monster and battle requires planning and thinking. You can't just go and slash things like in Zelda. You got to time your hits, dodge/block damage coming in because most creatures can kill you in 3 hits or less. If you like the Iron Knuckle fights of Ocarina of Time, imagine Dark Souls with fights like that on steroids.
The bosses feel threatening, more threatening than any game I've played because these are ancient beings that survived and they will tell you how they live that long. I beaten it a few months ago and now currently half way through the second game. Still love the first game just a little bit more but still a good game. Just a bit of advice, the leveling system is a bit vague in Dark Souls. Never level up resistance and check to see which weapons works best your stats. Each stats have a soft cap around level 40 and the weapon upgrades are more important than the levels themselves (equipment requirements being the only other important information). I'd recommend reading a wiki article about this.
I'm also starting to learn Dota 2 by reading all the guides and playing bot matches. Having a friend to play with is also nice (and I be willing to play with others when I get the chance). The only problem I have with Dota is because the matches require you to finish before leaving means that I really don't have time to play at times. You need a good hour and a half to finish most games safely without interruption. Hit me up if you or anyone else is interested. I got about 30 games down but I'm still noobish in the game.
The only other game I'm currently playing is Cataclysm: Dark Days Ahead. It's a roguelike game that includes a mod for pictures for those who don't like ASCII (text) graphics. It plays like Project Zombiod but has a ton more content. It's pretty awesome because it has the fallout vibe to it as well. The story is everything that went wrong for doomsday did go wrong. Your objective is to survive, collect, build a base, find a working vehicle (or repair/build one) and see how long you can survive. What I love about this game is watching other people play is actually pretty entertaining. They don't know what will happen but often they know how to get started. Which is great for beginners.
If you have a series of games you enjoy then maybe I can suggest some others.