Most most recently? I guess it's The Age of Decadence but I didn't really quit it for good. I was wondering what to play - I was looking for something simpler and even though the game said it's going to be hard, I decided to give it a try. Well, I died. In the tutorial. The game wasn't kidding around, so I decided to postpone it and play it later.
For something that I actually decided to just quit and never come back with the appropriate response - it was a couple of years ago but Kingdoms of Amalur: Reckoning. I played the demo and I actually knew what to expect from the game. It was not going to be great, but overall just OK, I was fine with that. I did wait for quite a while before getting it at a huge discount but when I did, I tried it and...my tastes had changed, so I couldn't really stomach it any more. It was mediocre in many levels which I had grown to dislike over the years.
Around the same time, I also tried RAGE - this one I had no experience with but I also got it at a huge discount and decided to give it a try...yeah, turns out it was a bad idea. It was just terrible. I had recently played Borderlands 2 and comparing that to RAGE was killing me, since I loved BL2. But even without that, the game really couldn't do anything I wanted correctly - people give Gordon Freeman shit for not being voiced, but he's actually fine[footnote]I keep wondering why people think he doesn't speak when he actually interacts with people and they respond to him.[/footnote], the protagonist of RAGE, however, was a disaster. You exit a "vault" (or whatever they were called in that game) and the whole world is in shit. Whatever. But some guy picks you up, starts spouting exposition at you and at no point the main character is like "Hold on, buddy, back up - can you fucking explain what any of what you said is? I'm hunted? Why? By whom? Who are these bad people? What happened with the world? I know that you know that I have been away for quite a while and I literally cannot know what you are talking about." That might have been fine if it wasn't for the gameplay. I went into the first dungeon you're sent to and guys start running at me. Fine, that's what the game is - shoot guys. So I did, I shot them in the head. And they lived. I gad to shoot the lowliest of enemies several times in the head in order to kill them. I wasn't even playing at an extreme difficulty, just at whatever was above normal and enemies were already shaping up to be bullet-spongy. I finished the dungeon and that confirmed it - enemies were eating far too many bullets than really needed. So I quit and never came back.