Software gives us a little taste of time travel ever day: "cancel", "undo", and "redo" are powerful tools that let us fix our mistakes. Ctrl-z and Command-z undo in most Windows and Macintosh applications respectively.

There's software that (may?) predate this pattern, notably Emacs and Vim and beginners usually struggle just to exit. I collected these in list on Github; treat it as a living document and add any ones you can find!