Hi!
I very much enjoy games which have some sort of time travel, for example Braid. I just hope there would be more games like this. Last week I participated in TriJam #125 and came up with a game about rewinding time. I wrote a tutorial for technique I used and wanted to share it here. Don't worry, it's not anything difficult, the tutorial's minimal working example has just about 60 lines of code.
Tutorial uses Godot, but there are some notes how some concepts convert into Unity/C# and the example code is very clear even without prior knowledge of Gdscript.
Have a read: https://axu-ap.itch.io/rewound/devlog/267320/time-rewinding-mechanic-tutorial