Thank you for playing and writing a review!
We hadn't really thought about the possibility of having the egg hatch sooner/later. Right now it hatches at a set time. After that, the idea is to have to feed, train and play with the little monster, while it grows as days pass, and having the monster's personality and abilities be affected by its interactions with the player.
We even got to design the sprites for different stages or evolutions of the creature, so we were a little disappointed that we didn't manage to use them in the demo.
When we tested the game we noticed the gameplay gets tedious in its current stage so we were also worried about that, sorry haha.
We also like Stardew Valley and we agree that could be interesting as well!
thanks!