Questions in UNDERTALE

hey anyone willing to help me on my Undertale game yes or no

anyone willing to help build my game on ROBLOX for free yes or no

vote

porfavor teminen la encuesta https://gamejolt.com/p/outer-nico-y-cata-con-estadisticas-voten-…

porfavor terminen la votacion

https://gamejolt.com/p/outer-nico-y-cata-con-estadisticas-voten-…

https://gamejolt.com/p/outer-nico-y-cata-con-estadisticas-voten-…

https://gamejolt.com/p/everyone-s-making-their-own-sonic-exe-hm-…
Yeah I'm getting nowhere with this so uh
Who should I make an exe of?
(Each community is just the game I use the character of)

This might be a really stupid Undertale question, but how do you fight Sans?

I did the Genocide run and he didn't fight me. I'm so confused.