A downloadable game for Windows

About This Project

This is a personal fan game of mine that I had been working on for a working / interactive screen cosplay! I'm a huge fan of Undertale and this boss battle in particular, since it was such a departure from the rest of the game. So, obviously that meant that I had to remake it from scratch.

How To Play

Move: Arrow Keys
Action: Z or Enter
Dodge as much as you can, call out for help, and fight to take down Flowey!

Visual Epilepsy Warning

Warning! This game contains flashing lights, static, and other such patterns, which could be potentially harmful to those who experience visual epilepsy! Play at your own risk, and take care!


This fan game has massive spoilers for the neutral ending of Undertale! So, if you haven't already, do yourself a favor and go play Undertale! It holds a very special place in my heart, and perhaps it will in yours, too.

More information

Published 229 days ago
TagsBullet Hell, fangame, flowey, undertale
Average sessionA few minutes
InputsKeyboard, Gamepad (any)


your_best_nightmare.exe (43 MB)


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This is probably the best Fangame for undertale!
So much effort is put into it!

I love this game <3


great job on this! this will forever be the BEST UNDERTALE FAN-GAME EVER

Made A Video On It ;)   

You Should Make More Battles Like This! Also Game Is G R E AT ! :DD


This is defenetly one of the best fangames out there, for me at least. Actually that's exactly what I wished for the original game. The original ps flowey may be insane already, but you just build what he lacked (especially the fact that it's 16:9 now)

Do you think you'll be able to port it for linux? I mean, thank god it's compatible with wine and despite the fact that when you die for the 3rd+ time the resume text isn't visible it still isn't that easy if it's not in the Itch library.

Also can you please add Y as an action key for the German layout.

Thanks for everything!