After returning to the Security Office, hand over the Data Diver for Clock Off, run Parachute.exe for the extended escape, or meet the New Game Plus requirements for the Secret Ending.
With the Mimic blueprints secured, you have reached Secret of the Mimic's endgame. The choice you make from here determines how Arnold's story concludes—and some routes will keep you exploring the Costume Manor considerably longer.
This page is the endgame hub: it explains how the endings work and directs you to the complete route for each of the game's three finales.
Endings Guide
Use the three route pages below if you want to begin a specific ending immediately.
The Endgame Begins...
After returning from the Tunnels and escaping Tiger Rock, you can end the journey immediately. Speak to the Dispatcher in the Security Office; he will ask you to hand over the Data Diver and close the case.
There is still much more to uncover. The three endings reveal major story details and clarify events from the rest of the game, but their requirements differ: Clock Off is immediate, Parachute.exe opens a new area, and the Secret Ending requires a full New Game Plus completion, a return through the Costume Manor, and collectible hunting.
This is also the point to explore the Costume Manor thoroughly. Executive clearance opens the secret rooms that were inaccessible earlier. The Mimic can still appear in costume rooms, so remain alert while searching.
Use this opportunity to search for the secrets and hidden story material Edwin Murray left behind throughout the Costume Manor.