Finally got the day/night gameplay loop (kinda) working!
Tomorrow I'll create some upgrades which can be bought with the collected resources.

Also I'll focus on the mechanic of tiles which are eaten by The Sea Monster
(it's those red tiles - each new day the monster will mark 3 of them and will devour them the next day, which effectively limits our gameplay space as the time goes and forces us to strategize)

Time to get a tiny bit of sleep now...