Sans Simulator is a fan-made Undertale battle game built around the fight involving Sans and the human. Instead of exploring a large world or following a separate story campaign, the game concentrates on combat. Depending on the version or selected mode, the player can fight against Sans or control Sans and attack the human. The setting, characters, attack patterns, and visual style are based on Undertale, but the simulator is designed mainly for repeating and practicing the battle rather than retelling the full original story.

Two Sides of the Battle

When playing against Sans, the player controls the human soul inside the battle box and must survive patterns made from bones, Gaster Blasters, gravity changes, and other hazards. White attacks cause damage on contact, while blue attacks require the soul to remain still to avoid damage. Sans repeatedly dodges direct attacks, so surviving long enough to exhaust him is part of completing the encounter.

Attacks and Game Modes

Different Sans Simulator versions provide several ways to practice or change the battle. Common gameplay elements include:

·         moving the soul with the arrow keys or WASD;

·         dodging bone patterns and Gaster Blaster beams;

·         reacting to gravity changes;

·         attacking when the battle reaches the player’s turn;

·         playing as Sans in versions that allow character control;

·         selecting individual attacks for practice;

·         using Endless or custom attack modes in supported versions;

·         repeating difficult sections until their patterns become familiar.

Progression and Controls

Sans Simulator does not use traditional numbered levels. Progress comes from surviving increasingly difficult attack sequences, learning patterns, and eventually finishing the battle. Some versions also include multiplayer or additional characters and variations of Sans, while others stay focused on reproducing the standard encounter.

The controls depend slightly on the version, but movement is generally handled with the arrow keys or WASD, while Z, Enter, or X are used for menu selections and battle actions. Success depends mainly on timing and pattern recognition. Players need to watch where bones appear, move before Gaster Blasters fire, stop during blue attacks when required, and conserve health through the longer attack sequences. Because failed attempts can be restarted quickly, Sans Simulator functions as both a standalone challenge and a way to practice the mechanics of one of Undertale’s most demanding fights.