This door indicates that to open it, you'll have to upgrade your GameLeaf's internal software.

At this point in the adventure, there are seven apartments connected to one another by their front doors.

You can update your GameLeaf by exploring each apartment and understanding how they work.

The highest version number that can be reached is 2.9.

Yes, there's a way to know where the batteries you've already placed into devices are located.

Look at the lower lefthand corner of your screen when you insert a battery into a device and it powers up.

You'll see a code made of one or two tetrominoes. This code tells you exactly where the battery is located.

Fael wrote down what he thought he figured out about the codes on a Post-it note, which he stuck to an antenna that was being repaired.

You're right, though the apartment still has four projectors, they're each playing four different videos.

The video projectors can be rotated, and the videos themselves can be "edited."

Take a close look at the videos, as well as the walls in the different rooms.

In the archive room, four diodes are connected to a dock. Four diodes=four video projectors.

Some antennas have moved, but they still work the same way they did earlier in the game.

The antennas and batteries follow the same tetromino-based logic.

One room contains spheres that you can connect to each other.

Even though it's invisible, this room has a floor, a ceiling, and four walls, like the six sides of a die.

Some bookshelves can move, provided you know their individual codes.

The code to enter into each bookshelf is always a word, and you'll have to figure out which one by using the objects placed on the bookshelf itself.

The bookshelf apartment is linked to another apartment.

Battery-powered wall-mounted devices in the bookshelf apartment allow you to open doors in the connected rooms in the other apartment.

If your GameLeaf is not at least at version 2.x, there won't be much for you to do in this apartment.

It is possible to take a look inside the closed rooms from the outside to better understand their structure.

The retro puzzles, as well as the arcade machine, allow you to view the closed rooms… from the inside.

Five observation points inside the rooms will allow you to activate five locks marked with an eye.

To activate the telephones on the walls, you'll have to use another type of telephone that's in a different apartment.

All of the telephones on a single wall are linked to one another and form a "map" that you can explore.

The starting point for each map, and for moving around on said map, is a red wall-mounted telephone.

There are different types of wall-mounted telephones. By picking them up, you can figure out what kind they are: hallway, door, key, or trap.