Grow Sky is a game about engine building, both mechanically and thematically, as players compete to become the best sky ship master by flying and developing their own sky ships.

Each round, players roll and draft dice to determine their ship's actions, some combination of flying to gain resources and medals, developing their ship for more effective future actions, or going on standby to gain resources. Most actions have a mechanic of their own, from the polyomino-filling of engine room development to the upgradable rondel of each player's flight track.

Over the course of the game, players compete to gain medals and to complete two types of missions - route missions, which grant benefits only to the first person who completes them, and goal missions, which rank the players in order of completion. These missions may range from having specific resources available to specific configurations of parts in the engine room.

The game proceeds until someone gains 15+ medals or fills up their engine room, at which point the final round proceeds, and the player with the most medals wins the game.