Art:
I like the feeling of playing Spyro/Banjo-Kazooie when walking around. I would continue to add more quirky additions like the beer stand at the beginning, as well as the fun colors, that way players will always have that other-worldly experience exploring, when not actively completing the main quest.
Design:
Play-testing the distance of sight for the player when walking around would help establish when/where to add certain attractions, pulling the player the direction you intend via imagery in the near distance.
Gameplay:
I think the nature of the game as a 3D platformer inherently makes players want to continue and collect/complete events in the world. I suggest adding/hiding more items around the level to allow further engagement outside the main quest.
Also, there seemed to be a slight lag when turning around the character, either from the directional control from the mouse, or key combination with the forward and left/right inputs.