Bad Time Simulator is a fan-made recreation of the Sans boss fight from Undertale. Instead of playing through the full RPG, the player goes directly into the battle and controls a small heart representing the SOUL. There is no separate story campaign in the simulator itself; its purpose is to reproduce the combat sequence, attack patterns, and menu-based turns of the original confrontation. The project was created by Jcw87 in Construct 2.

Surviving Sans’ Attacks

During Sans’ turn, the heart appears inside a battle box and must avoid bones, Gaster Blasters, platforms, and gravity-based attacks. In red SOUL mode, the heart moves freely in all directions. Blue SOUL mode changes movement by introducing gravity, making the heart behave more like a platforming character that must jump over hazards. White attacks cause damage on contact, while blue attacks require the player to remain still when they pass through.

Different Ways to Practice

Bad Time Simulator includes several modes designed around the same Sans battle. Normal Mode runs through the complete attack sequence, while Practice Mode helps players learn difficult patterns. Endless Mode continues attacks until the player runs out of HP, and Single Attack Mode allows one specific pattern to be selected and repeated. The original project also supports custom attacks created from attack data.

Players need to:

·         move the SOUL with the Arrow keys or WASD;

·         press Z or Enter to confirm menu selections;

·         use X to cancel or return;

·         dodge bone walls and moving platforms;

·         avoid Gaster Blaster firing lanes;

·         adapt quickly when gravity changes.

The attacks follow recognizable patterns rather than appearing completely randomly. Learning the position of gaps, the timing of platform jumps, and the direction of incoming beams becomes important during later parts of the fight. Some attacks throw the SOUL toward the walls of the battle box, while others combine bones and platforms and require controlled movement instead of constant dodging.

Learning the Full Sequence

Bad Time Simulator does not use character levels, equipment upgrades, or a traditional map. Progress comes from surviving farther into the Sans fight and memorizing attacks that caused problems during previous attempts. Practice and Single Attack modes make it possible to repeat difficult sections without replaying the entire battle, so completing the simulator depends mainly on timing, precise movement, and learning how each attack pattern works.