Board Thread:General Discussion/@comment-10452902-20170507091901/@comment-28517148-20170507155140

Option to spare Sans is just a prank. Toby Fox has known that Players will be trying both possibilities - sparing Sans to see what happens, and after that, killing him only to get an altered ending. However, this is player's perspective. From Sans' point of view giving Frisk possibility to spare is really a way to effectively end the genocide, just like you said. However, damage has been done, so only Reset can help here. Does Sans know about that? And now comes to mind: are we actually fighting against Sans or the game creator? This way or another, you're gonna have a bad time.