Bad Time Simulator — Play the Sans Fight Free Online

What is Bad Time Simulator?

Bad Time Simulator is the Sans fight from Undertale, lifted out of the game and put in your browser. In Undertale it is the last battle of the Genocide route, the one the whole game warns you about, and it is famous for being the hardest thing in it: a skeleton with one hit point who dodges every attack you make and answers with bones, Gaster Blasters and gravity until your patience or your health runs out. jcw87 rebuilt the fight in Construct 2, attack for attack, with the original music and dialogue, so that it can be practised without playing the whole route first.

You are the red heart. The battle box is your whole world for the next twenty minutes, and the only skill the game asks for is moving that heart to where the bones are not. It is a bullet-hell game with one boss, and it is fair in the way the best of them are: every attack has a safe answer, every death is your fault, and after enough attempts the impossible pattern turns into a dance you know by heart.

How to play Bad Time Simulator

1. Press Play above. Use a keyboard: the fight needs four-direction movement and a confirm key.
2. Choose a mode. Normal is the whole fight; Practice and Single attack let you drill the parts that kill you; Custom attack builds your own sequence; Endless never stops.
3. On your turn, pick FIGHT and press the confirm key when the bar is in the centre. Sans dodges; do it anyway, because the fight ends when he gets tired, not when you get lucky.
4. On his turn, move the heart with the arrow keys. Touch nothing white. Stand completely still for anything light blue.
5. When the heart turns blue, you fall. Jump with Up, steer in the air, and land on the platforms he gives you.
6. Survive to the special attack, sit through it, and then survive the last gauntlet when you try to end your turn. Then you win.

The mistake everyone makes: pressing a direction during a light-blue bone. Blue means “do not move”, and the reflex to dodge is exactly what kills you. Take your hands off the keys.

Bad Time Simulator controls

The attacks, and how to survive them

• Bone gaps. Walls of bones with one opening that changes height. Look at the gap, not the bones, and be at its height before it reaches you.
• Sliding bones. Rows that sweep across the floor and ceiling. Small hops over the short ones, stay low under the tall ones.
• Blue bones. Light-blue bones pass through you harmlessly as long as you are not moving. Freeze. Every input, including a diagonal you did not mean, counts as moving.
• Blue soul. Sans flips your gravity and you drop to the floor, walls or ceiling. Jump over the low bones, duck the high ones by staying grounded, and use the platforms he provides: they exist so that you can survive.
• Gaster Blasters. Skull cannons that appear, charge for a moment and then fire a beam across the box. The charge is your warning: read the angle, step out of the line, and never stop in the middle of the box.
• Platform blasters. Ride the moving platforms while blasters fire from four sides. Keep moving and change platform when yours drifts into a beam.
• Random blasters. Beams from every angle in quick succession. Stay near the middle of the box and make short, late dodges rather than running to the edges.
• The special attack. Nothing happens. Sans waits for you to move. Wait. Then, when you try to end your turn, the last and longest gauntlet begins, and it is only what you have already survived, faster.

Tips for finally winning

• Practice mode is the whole game. Nobody clears Sans by starting over from the top forty times. Drill the attack that kills you until it is boring, then go back to Normal.
• Tap, do not hold. The heart moves quickly and most deaths come from overshooting a gap. Short taps put you exactly where you looked.
• Learn the music. Megalovania is the timer. Attacks change on the phrase, and after a few runs you will know what is coming from the bar it is on.
• Respect Karmic Retribution. Purple health drains. A run that takes five small hits early is dead before the blasters; a clean start is worth more than a heal.
• Heal at the right moment. Items are limited. Use them when the drain has stopped, not in the middle of a hit, or half the heal disappears.
• Blue soul: land, then look. Jumping early into a bone you could have walked under is the most common blue-soul death. Ground yourself first.
• Do not rush the special attack. It is a test of patience by design. Walk away from the keyboard if you have to.

Playing on a Chromebook, laptop or desktop

The game is light, loads in a few seconds and runs in any modern browser. It wants a keyboard, so a Chromebook or laptop is ideal and a phone is not: the four-direction dodging has no touch controls. Use the fullscreen button under the player so the battle box is large enough to read, and if the game feels choppy close other tabs first; Construct 2 games share the browser’s single main thread.

Why Bad Time Simulator is still worth playing

Undertale is about choices, and the Sans fight is the consequence of the worst one. Taken out of the game it becomes something purer: a boss fight that is exactly as hard as it was in 2015, with no story to soften it and no reason to be there except that you want to beat it. Most people who open it die in the first bone gap. The ones who keep going find that a fight which looked like chaos is a long, memorable sequence, and that clearing it is one of the best feelings in browser games.

Frequently asked questions about Bad Time Simulator