I gotta say, it is an incredible honour that someone would even compare my game to an awesome game such as Cosmoteer! Thanks for that.
Technically, there is a creative mode in the game. If you join the discord and ask around, I'm pretty sure someone will be more than happy to share all the little secrets about the game! I would put it here, but then everybody can see it and it wouldn't be so much of a secret anymore.
But an official creative mode is being dreamt up. Its not exactly creative mode, but if you play long enough you should have all the items to where is basically counts as creative. So something like a sandbox with progression.
Thanks for your feedback and I'm glad you enjoyed it!