Mysterious Maze

Escape from the 3D maze!
The rule is simple.
To escape from maze, You have to get a gem and opening the door of the goal.
Gems may not be found easily.
Find it, solve the mystery and get a gem!

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The basic operation is to switch the 'move-mode' and 'view-mode' to advance the game.

Use direction buttons in 'move-mode'.
To go forward or backward, tap the up or down arrow button.
To change the direction, tap the left / right rotate button.

When you find a gem, tap it and get it.
The goal door will not open without getting gem.

Swiping the screen changes to 'view-mode'.
After changing the view, double tap to return to 'move-mode'.

If you can tap something in the screen, you may be able to take action by tapping it.
In particular, the paper attached to the wall may be a hint of something.
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A huge maze is waiting for your challenge.