Fate/Stray Night

Shirou walked out of the Holy Grail War with his enemies beaten and three girlfriends to show for it. That should have been the ending.

Instead it's just the start of the school year, and the Emiya house is now packed with Saber, Rin, and Sakura, plus Rider, Illya, and Taiga all under one roof. Peace lasts about as long as it takes Shinji Matou to notice how many women live there, and he's already decided they're all his to go after.

You move through a sandbox version of the house and school, poking around locations and characters to trigger the scenes tied to each one. Small ongoing threads, like a manga club side-story and a babysitting encounter in the park, keep building the further you dig, so it rewards checking back on people rather than rushing through once.