Undyne the Undying Fight Simulator

Keys

Arrow keys move the heart and walk the menus. Z selects. X cancels. Press Play, then click inside the frame. Until that click, the keys do nothing.

A phone cannot play this. The fight is arrows only. Players on the project have asked for WASD, and this build does not have it.

The title card reads Undertale, Undyne the Undying, with Play and Options. The battle opens on the line that the heroine appears, at LV 10 with 56 HP. The green shield works, and the menu is Fight, Act, Item, and Mercy. Lose and you get a game over. Players on the project talk about finally beating her, and about the fight feeling accurate. Some of them say it took a long time.

The heroine

Undyne the Undying is the third boss of Undertale's Genocide Route, in Waterfall. She chases you through the area. Monster Kid gets in the way and confronts you on the bridge. Undyne jumps in to protect them, and one strike wipes out her HP. She lies to Monster Kid about how she is, tells them to run, and refuses to turn to dust. That determination, and the hopes of monsters and humans, is what turns her into the Undying form.

She has 23000 HP, attack 99, and defense 99. The reward is 1500 EXP. Act is Check only. Check calls her a heroine reformed by her own determination to save the earth. The line you will hear is that you are going to have to try a little harder than that. The music before the battle is But the Earth Refused to Die. The battle music is Battle Against a True Hero. Serious Mode is on. You cannot spare her or flee, even when the heart is red.

Every hit on her is multiplied by 21. A hit under 600 deals 600 to 666 instead. Her attacks deal 8 to 14 damage. Your LV can be anywhere from 8 to 13. Higher LV means more HP, and in this fight each LV also removes one invincibility frame, so you get 17 to 21 frames instead of the usual 30.

How to dodge

While the heart is green you are locked in place. The shield faces up, down, left, or right. Blue spear arrows turn red when they are the next to hit. Block the red one. Some arrows are slow and some are fast, mixed in the same wave.

• Yellow arrows flip to the opposite side as they get close, so you block the side opposite the one they came from. That starts in the second green cycle.
• A later green attack turns the red next-arrow mark off. A slow red arrow is mixed with fast blue ones from every side. Do not trust the colour on that wave.
• One green wave runs in circles: four yellow, four normal, four yellow. The first two groups go counter-clockwise. The last group goes clockwise.
• She keeps a Challenge number. Getting hit while the heart is green lowers it. The arrows slow down, and the green attacks last longer.

The first red cycle is a tiny box with three columns of spears shooting up. There is a pixel-wide safe spot between the left column and the centre column. In the real fight, hold the back button to ease into it. Otherwise stay near the top and change columns when a spear appears under you. After that, spears come from every direction on a bigger board. Keep moving. They cross the whole board, so backing into a corner does not save you.

The second red cycle is rings of seven spears closing in, twice, and then you are green again. After the last green attacks, the fight loops. Rings of six spears converge, and the gap between rings shrinks. Move in big circles and slip through the gaps. A spear cannot hurt you once the ring has already closed. Rotating rings of eight spears are the attack a no-hit guide calls her hardest: stay mostly still, wait for an opening, and account for the spin, which slows as the spears come in. Fast single spears aim at you. Then a faster version of the three-column box.

In this project, arrows move, Z selects, and X cancels. The real fight's slow step into the column gap is the back button. There is no WASD.

What to equip

Ballet Shoes are 7 attack and end the fight sooner, about 15 to 18 attacks instead of a longer set. The Torn Notebook is 2 attack, 6 invincibility, and 55G. The Cloudy Glasses are 5 defense, 9 invincibility, and 30G. Both of those are sold by Gerson in his Waterfall shop, and the extra invincibility frames are why people bring them. Ballet Shoes and the Old Tutu cannot be picked up once you have fallen into the dump.

Gerson's Chapter 4 hammer is a separate green-shield fight. Gerson fight simulator is the partial Hammer of Justice build.

Other fights

The other Genocide boss on this site is the Sans fight simulator .

The six human SOULs show up in the Omega Flowey fight simulator .

Another copy of this spear fight is on Deltarune Fight .