Sea of Stars: main story about 20 hours; story with some extras about 32.7 hours; 100% completion about 43.7 hours. These are IGDB player-submitted averages from 8 submissions, not a deadline or a prediction of your pace.
Source: IGDB player submissions
Community playtime data is not available for Sea of Stars yet.
Game Tales keeps what happened between you and a game in one Tale you can keep building.