Spoiler: SPOILERS FOR MASS EFFECT 3 AND THE LAST OF US! At least in ME3 you get to destroy the Reapers with your choice of coloured beam. For me, probably The Last of Us. The fact that Joel destroys humanity's last chance for a cure just so he can keep Ellie alive was understandable, but it just maies me hate Joel, the ONE CHARACTER YOU SEE FROM THE VERY START OF THE GAME!
Spoiler: Mass Effect 3 Thing is, with two of those beams you don't even destroy the Reapers, and with one you destroy ALL AIs, including one of your own team members, two if you count the Legion-replacement... and as the choice setup implies, whichever one you choose implies that the person represented has the correct perspective, possibly rendering the events of ME1 entirely moot.
Oh yeah, I almost forgot - L.A. Noire is said to have a surprisingly weak ending, given the number of plot points they had running... I really hope that Rockstar let a small team fix it up for the Switch release.
Xenoblade Chronicles X's was pretty dire, although it didn't have much of a story to begin with. But to end on that kind of cliffhanger...no. It was Golden Sun: Dark Dawn all over again. Spend years waiting for the sequel, be profoundly disappointed by it, and have no real conclusion so you can't even close the book on it. Maddening. Tales of Zestiria had an awful ending, but then, Tales of Zestiria was an awful game, so for it to have a satisfying conclusion - even after postgame DLC! - was too much to hope for I suppose. Several years later I'm still trying to figure out what on earth happened in Lightning Returns. After the end of XIII-2 I actually had hopes that the trilogy, which started so badly, would finish on a real high note...but it went back to its roots and is one of the worst endings I can think of for how pointless and utterly nonsensical it is. Also, Tales of Xillia 2's True Ending. This one I want to rant about. Spoiler The game spends the entirety of itself pushing the view that parallel worlds do not matter onto you - which is good, considering you spend half the game murdering alternate versions of major characters - and then has Ludger, the protagonist, sacrifice himself for Elle, who is from a parallel world, and therefore doesn't matter? When you take into account the game's Good Ending - where Ludger finds the woman he'll marry and who will give birth to HIS Elle - it makes even less sense for these two endings to be this way around. Even the Bad Ending was better than the True Ending. Despite what people say about it, I don't think Mass Effect 3's ending was THAT bad. It just didn't take your choices into account enough. But in and of itself it was a fair conclusion. If you want a bad ending in a Bioware title...play either Dragon Age II or Dragon Age Inquisition. Those make ME3 look like the pinnacle of storytelling.
No Man's Sky. In the long list of disappointments that game was, the story ending is at the top of the list of trash. Spoiler You followed the Atlas path to the end. You spent many a resource getting there. And what do you get? The game basically just says "You did it!". That's it. The dialogue says that you use the Atlas station to "create a new star" somewhere in the galaxy, but it doesn't actually do that, it just says it to make it feel like you did something. As well as that, one of the primary goals of the game is to reach the centre of the galaxy. Because it's there, I guess. Wanna know what happens when you get there? Spoiler You get warped to a random planet on the edge of the galaxy, with literally all of your things broken, requiring as much to repair as it takes to craft in the first place. In short, it resets you to zero, as if you just started a new game.
I'd say that Sonic Forces had a bad ending, but that really isn't fair to say - the truth is that the plot itself was incomplete (either being rushed or being lazy). Perhaps a better case of this would be Ace Attorney 5 (Dual Destinies for those of you that go by subtitles). The rest of the game is generally passable before then, but the ending and buildup thereto sounds, for lack of a better word, rather contrived. The Ace Attorney games always tend to end with rather surprising plot twists of some kind, but AA5's felt like the plot twist was added simply for the sake of having a plot twist. There's also Shadow dying at the end of Sonic Adventure, but we don't talk about that one.