How about adding an underground area, like a second area to the game? It contains more crystals, games, parts, Guardians, e.t.c. Just like the "Overworld", a special boss will spawn in offering wells - The Kraken. The Kraken, unlike the Leviathan, will not attack players unless it is attacked first. Just like the sea tales of old, it will be mainly composed of tentacles coming from the ground. If you do not attack it, but instead give it crystals, you will also get rewards that way, but they are different. Anyway. This is just a thought that came to my head. It definitely needs further refinement.