This is a really great first game and the fact you made it in 3 days is very impressive. I like that to find the true ending of the game you have to avoid all of the goals. It's kind of like an easter egg hunt. When I got to the end I immediately noticed the reference to the Stanley Parable but I think you could have expanded on the narrator a bit more. It would have been nice if the further to the end you got, the harder it was to avoid the flags because the narrator is trying to get them to hit you.
Overall though you've done a really good job and I hope you enjoyed making your first game!