Really loved your way of storytelling. I had a lot of fun playing even though the game is quite short.
Before the endboss fight against the slimeking started, during the dialogue I could move my character and jump off the platform into the white void. It wasn't really a problem because I got teleported to the fight after the dialogue, but it would be nice to fix that if you continue working on the game, which I would really encourage you to as it is a very nice concept.
The only things I would improve are collisions and some visual stuff. Sometimes the collision with a spike seemed unfair, I lost health while not really touching it. Maybe you could edit the hitbox of the obstacles to make them a little smaller, that would increase the fairness and fun in my opinion.
And it would be nice if the spikes had an outline to easier distinguish them from the background.
Other then that it was a nice game and Ollie was really cute. The dialogues were nicely implemented as well.
(Ps. I would appreciate it if you could try out my game)
Keep up the good work (9-^)