Beginner's Guide
Everything you need to know before diving into Detective Grimoire's submarine murder mystery.
How the game plays
The Mermaid Mask is a point-and-click adventure with a strong focus on investigation. You move between hand-painted rooms on the Mortuga submarine, click objects to examine them, and talk to suspects. Many clues are fully 3D objects you can rotate and zoom to find hidden details.
Core loop (verified from Steam store + ninewiki walkthrough):
- Explore a room and click every object of interest.
- Collect evidence into your case file automatically.
- Interrogate suspects and present evidence to expose contradictions.
- Solve environmental puzzles to unlock new areas.
- Deduce the truth by building logical sentences from evidence blocks.
Investigation tips
5 things the walkthroughs agree on
- Rotate every 3D clue fully. Clues like the Glass Eyeball and repaired compass have vital details on their reverse sides.
- Exhaust suspect dialogues. First-time introductions often unlock new investigation topics.
- Check your notebook. It tracks active lines of inquiry and tells you what still needs a conclusion.
- Use the hint system. It gives thumbs-up/thumbs-down feedback without any achievement penalty.
- Keep a backup save before the final confrontation. Some achievements are missable if you enter the finale without exploring every optional room.
What to do if you're stuck
If you hit a progression block, the most common cause is an unread clue reaction or an incompletely inspected 3D object. Before backtracking, re-examine your newest inventory items and revisit the room where you found them. If a puzzle still won't budge, see our Puzzle Solutions page for the exact answers.
Sources: Steam Store API (appid 1696770), fetched 2026-07-19; ninewiki.com walkthrough, 2026-07-17; grindnstrat.com puzzle solutions, 2026-07-18.