Japanese by Example
Learning through examples in manga

Case closed at curfew time with 門限

三ツ星カラーズ » Volume 4 » Page 78

After finding evidence of a UFO encounter, the group Colors sets out to find aliens. The case is cut short when the 5PM bell chimes, signalling that the young trio has to head home for the day.

斎藤(さいとう):
「ああ門限(もんげん)か。ゲームオーバだな」
"Ah, curfew time? I suppose it's Game Over."