From my observations, the secret to an immersive atmosphere is not detailed or realistic graphics, but consistency. If everything in a world looks consistent, it'll automatically be immersive in one way or another. Think of Minecraft and maybe the Pokemon series...
It looks like a pretty sweet and cute game! But yeah, if I were to buy it I'll wait for a sale too.
Totally agree, consistency is a key part of imersiveness, but it's a little bit too general. For a good immersive experience, you, as a player, must be able to feel like you belong to that world, Minecraft is a very good example.
For this experience to be consistent, everything must be aligned, from graphics, to game mechanics, to music and story(optional).