Read the letter (1/11) on the desk. There is a pressure pad in the corner of the room near the desk - when you stand on this both doors open across the room. Pick up the chair and the trash can and place them both here, which should contribute enough weight to keep the smaller door open. Look at the shelf just to the left, to see that there are 3 small spheres, in the order of black, brown and orange from left to right. Now head through the opened door The Chase Is On!.
Read the next letter (2/11) on the floor, then rearrange the large spheres on the stands into the same order as you just saw in the previous room: black, brown and orange I Am The Keymaster. Now you can pick up the large globe at the top of the stairs. Carry this back to the previous room. Move the chair and trash can off the pressure plate, and place the globe here. Now you can go through the large door and up the stairs.
Read another letter (3/11) on the floor. As you step forward, pay attention to the order of the lights that flash green above the 8 doorways here. You need to go through these doorways in the same order, each time reappearing at the beginning of the hall:
Now the back wall will open up and you can proceed Are You The Gatekeeper?.
Read the next letter (4/11) on the table here, then pick up a flare. If you get stuck in the darkness here you will have to start this section again. Light the flare and run to the yellow light over to the left. Grab and light another flare, then run to the next yellow light in the distance, jumping and knocking down some shelving along the way. Take another flare and light it, as you run over a bridge and crouch beneath a piece of timber to reach the next yellow light (it is actually slightly faster to jump over the left side of the bridge as you reach its far side than to crawl). Pick up the next flare and light it, running towards a relatively dim light to the left. With this one, you need to open a gate and keep running towards the next light. There are no flares here, so just run towards the door ahead - the lights will go out but you should still make it through Departure.
You will hear music start up. Go through the dark door into the next room.
Read the letter (5/11) on the table to the right in this lobby area. Go into the women's restroom and open all the toilet stalls to find another letter (6/11). Note the large silver statue in this room, then return to the lobby area. Go into the men's restroom and open the cabinet at the end to find 4 different spray cans. Also note the large silver statue in this room, then return to the lobby area again.
There are 2 smaller statues out here, that are orange (beneath the portrait of a woman) and purple (beneath the portrait of a man). Use the red and yellow spray cans on the statue in the women's restroom, and the red and blue spray cans on the statue in the men's restroom. If you make a mistake, you can use the white spray on the statues to start again. Once they are both correct, the entire area will darken and turn red Contents Under Pressure.
Go out to the lobby area and crawl through the fireplace. Read another letter (7/11) in the darkness here, then continue forward.
Go forward, then click on the vent beneath you to fall through to the starting room again. Search the floor to find a letter (8/11), then pick up the trash can and chair and place them on the pressure plate like you did before. Go through the small open door and find another letter (9/11). Collect the 3 large spheres and place them in order on their stands again Red Means Scary. The glass panel is already broken anyway, so you can go ahead and pick up the large globe. Place this on the pressure plate in the previous room, then go through the large door and up the stairs.
Read the next letter (10/11) on the floor, then watch the lights above the doors again. These are in the same order, but this time you will only need to go through the first two (and will need to avoid obstacles to reach the second one):
Keep going forward and drop down through the hole at the end.
Read the last letter (11/11) on the table here Time Enough At Last, then pick up a flare. Light the flare and run to the yellow light as you did last time. Grab another flare and light it as you run to the second yellow light, again jumping and knocking down some shelving along the way. Pick up another flare and the lights will go out - this time light the flare and run back to the previous yellow light. Grab another flare and light it, then head towards the white doorway in the base of the lighthouse Wake Up!.