Can I beat Sans Undertale and still get a refund?

Is it possible to buy Undertale, play through the entire game and beat the hardest bosses, and still be able to refund the game on Steam?~~~Music - Undertale

Essential T-Shirt

Undertale: I beat sans. | Essential T-Shirt

Who would win, Sans Undertale or Omega Flowey? - Quora

Both may be a problem : r/Undertale

Sans, Undertale Wiki

spoilers!)If you end your genocide run after being dunked by sans

I beat Undertale Genocide without getting hit

Endings - Undertale Guide - IGN

Can I beat Sans Undertale and still get a refund?

What are the requirements to fight sans in Undertale?