Very nice game! The scope was set perfectly for a game jam. The graphics are very pretty and fitting. I love how minimal the game is. First I was missing some background music, but silence actually fits the vibe very well with the animal noises. My only criticism would be that I think that the Dark and Light theme could have been incorporated more into the gameplay. Also, a "Restart" or "Go back to menu" button would be nice, because sometimes I already know I messed up in the beginning. :D

What a wonderful puzzle!

I need to think carefully about what to do (create) next

I love the overall visual style and the amount of polish that you were able to accomplish in just 30 hours. 

There maybe could have been a bit more interaction with the day/night apart from splitting the choosing and execution phases, like making the animals day/night active and then having execution phases for both day and night. This way the light and darkness would have more impact on the game cycle itself.

Apart from that the goal and vision of the game are very clearly communicated and with a bit of trial and error you can build a fully functional exosystem, great job :D