Or, Save Scumming: The Game.
You are the Harbinger, brought into the world to stop it ending, as Voden, the great snake monster of death keeps eating everything. Unfortunately, you keep being a bit slow, and so the day constantly resets on you, and only when you finally follow the correct path, can you save the day.
Which translates to replaying the same events over and over, but with four different characters by your side, each having a different experience in this one last day. As you dig through the days events with each character, you uncover secrets and keys to doors that you keep for the next run through, and can use with a different person, allowing a slow progression through the multiple possibilities.
The trouble is, that progression is almost entirely done by fighting. The levels contain small touches of variation, such as explosive barrels and the occasional flamethrower, but it's mostly a slog of slicing your way through a collection of relatively similar enemies. There are occasional bosses, but they don't add much by way of interest.
The plot is reasonably gripping, so I got through all of it in the desire to see the end of the story, and the dialogue is generally funny, with decent quips in combat or just exploring. The multiple timelines idea is a nice one, though could have been expanded upon, with the major problem being that all the changes simply alter which area you happen to be fighting in that particular day.
I enjoyed the concept, and the overall story-telling, but by the two thirds mark, it felt like I was plodding through the gameplay in order to see the story.