Sunset. It was a walking simulator back when they were all the rage.
You might think including walking simulators is cheating for a 'most unfun' game rating, but no matter what game comes to mind when you think of 'walking simulator', Sunset is more boring than that.
If you've played this type of game, you'll know that the best ones are the ones that have their plots unfold in interesting and engaging ways. There isn't a lot else going on in these games so a good plot and interesting ways to engage are paramount for this genre.
Sunset had you walk through an apartment to guess what object to interact with to advance the plot in a completely linear manner, driven entirely by post it notes. The plot was also pretty basic for the genre too.
How this game got 9/10s, 4/5s and a game awards nomination is fucking mystifying. The reviews talk about some deep commentary about civil wars or some shit, but I was too bored out of my mind to notice anything other than a high-schooler's attempt at writing about war. It's so far up its own arse about its 'war is bad' message that it forgets that it needs to convey it in an interesting way.
The game was received so badly by audiences that the developers just noped out of the video game market.