10 Video Game Endings You Weren't Supposed To See
5. You Dirty Hacker - Undertale
Undertale has a number of endings you were most certainly meant to see by completing new runs of the game, but there's an additional one which can only be accessed through the most cheekily nefarious of means.
By opening the game's files in a hex editing program and changing certain values, you can alter the game's state to one which shouldn't be possible.
And so, if you reload the game after editing the files, the end credits will roll, before Sans shows up, insists that this ending isn't supposed to be seen, and then declares you a "dirty hacker" and vanishes into the night.
Now in fairness, Undertale creator Toby Fox evidently knew that curious players were going to tinker around with the game's files, so in a sense he did intend for folks to find this ending - after all, why make it at all? - but in conventional play there's simply no way for folks to find it, let alone be aware of its existence.