I could probably come up with worse sequels if given more time, but two jump at me immediately.

My mind is telling me Trine 3. The game sets up a whole story, and then just ends 1/3 into that story. It was hugely disappointing when I played it. However, I loved playing the game. Everything up until the (premature) ending was great, so that isn’t my pick.

Instead my pick is Ori and the Will of the Wisps. The game is good, but it is just the first game again, almost beat for beat. At least that is how I remember it. I was so excited to play it, but the whole way through I felt like I had already played the game before. I managed to get to the end of the game, but I had almost given up on the game by then. It was “more Ori”, but that was not what I wanted, I wanted to see how they would evolve Ori. Afterwards, whenever someone would ask if I recommended the game I would say that I 100% recommend playing either game, they are both great, but once you have played one don’t bother with the other.