You start inside this cave because Frisk (you) fell down and meet this flower called Flowey, lets just call this flower the flower you will hate at first.
There's a lot of ways you can play the game, netural which is friend some, kill some, etc. (1/2)
Passive which is friend everyone, True pacifist which is getting the true ending. And genocide, you kill everybody, but if you go there, you're going to have a bad time. Cause two bosses you will have to fight are really damn strong. You can learn multiple pasts/histories of a lot of characters within most of these runs, doing certain things can trigger events/dialog/secrets and such. (2/2)
In the boss fight of Flowey (Omega flowey), he "deletes" your file and keeps you at this stage where you can't escape. Only way you can get rid of it is deleting 2 files that keep data of what is going on and keeps it.
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