How long is LEGO Batman: Legacy of the Dark Knight?
Roughly 10–12 hours for the main story across Prologue + 6 chapters. ~50 hours for a 100% completion run with all 200 WayneTech Caches and 23 Red Bricks.
The campaign breaks into a Prologue and 6 main chapters with around 29 named missions. A straight playthrough runs 10-12 hours. Hunting every WayneTech Cache (200), Red Brick (23), Skill Brick (30), Puzzle Room (121) and themed-item set pushes a 100% run to about 50 hours.