Titan Souls: main story about 3 hours; story with some extras about 3.3 hours; 100% completion about 7.8 hours. These are IGDB player-submitted averages from 3 submissions, not a deadline or a prediction of your pace.
Source: IGDB player submissions
Community playtime data is not available for Titan Souls yet.
Game Tales keeps what happened between you and a game in one Tale you can keep building.