What is the Neutral route

The neutral run in undertale Is a run where you spare some monsters as well as kill some. This is usually the first run players go through due to lack of knowledge of the other routes.

ending

the ending of the neutral route has you sparing asgore only for flowey to kill him and then absorb the 6 human souls. After this your game will crash and when you reload flowey will battle you in a hidious transformation. This fight requires you to stay alive unti lyou reach out to the souls and use their power to beat flowey.