The complete walkthrough for the tricky third chapter.
First, tap on the box on the ground right next to the ambulance and pick up the cleaning spray. Now tap on the license plate of the ambulance and use the cleaning spray on it. On the back of the ambulance door, enter the code revealed on the license plate: 5728. Take the crowbar from the back of the ambulance and use it on the driver's door. Tap on the steering wheel, turn the engine on, then note the colored lights that appear on the ambulance's rear doors, then enter those colors in order on the exit door control pad.
First grab the CD case from the bookshelf, dismantle it, and then use the CD in the computer. This will reveal the formula C4+A3+B1-E3. Imagine the bookshelf as a spreadsheet, look up the relevant numbers written on the objects, then perform the calculation. Enter the result (3677) on the safe to the right of the bookshelf, take the key, and then free yourself from the room.
First grab the ID card from the drawer beneath the projector, along with the purple clipboard sitting next to it. At the bottom of the ID card is a number 1485. Use this to open the combination lock on the suitcase next to the projector. Take the USB stick inside the briefcase and use it on the projector. Zoom in on the projected skeleton and make a note of the different body part names. Now look at the clipboard. Think of the date as a crossword position, then match up the name with the body part.
You need to fill out the safe's control panel like a crossword, using the dates as coordinates, and the body parts as the words. Now place the object inside the safe on the lectern to reveal the code 31371 in the object's shadow. Enter this in the control panel to leave the room!
Grab the two pool cue components and combine them. Now use the complete cue to knock a coin from the vent. Use the coin on the vending machine to retrieve a can of soda. Take the cubes of chalk from the microwave and the sofa, the floor, the pool table pocket and from the crumbled up paper in the wastebasket. Use the chalk cube clues to connect the wiring of the letters in the fuseboard to the correct color. Now use the number clues on the soda can to connect the correct number to the correct color. This will turn the television on, giving you the new code of blue, yellow, red, green, purple. Apply this code to the crumbled up piece of paper you collected from the wastebasket to get the exit code: 43158.
Tap on the bedsheets to expose the teddy bear. On the machine next to him you need to work out the averages for the yellow and red hearts. For reference, yellow is 75 and red is 90. Grab the scalpel from the tray in front of you and use it on the teddy bear. Enter 75 and 90 on the yellow and red sections of the teddy bear's heart respectively. Pick up the key card from the teddy bear and use it on the door panel to reveal the number 8888. Grab the x-ray from the sink and use it on the whiteboard to get an incomplete image. Combine these lines with the code 8888 to get the word 'Push' which you need to enter into the exit door panel. Proceed to the next room.
Open the bedside table drawer and take the knife. Grab the string of beads, the bottle, the piece of cloth and the rope from underneath the bed. Grab the piece of paper that lies under the left-hand bed's pillow. Use the beads on the window ledge to draw the blind. Combining the two images on the window reveals the word PLEDGE which should be entered into the laptop. You'll then be given a code that reads: (^^) which uses the keyboard numbers 9660. Now combine the bottle and the cloth, and use the finished product on the red house featured on the painting on the wall. Use the knife on the red X that's revealed, then enter the code 9660 on the safe. Take the key from the safe and use it on the window, then use the rope on the radiator so you can escape through the window!
Tap through all of the drawers and shelves until you have the following in your possession: three bottles (anti-B, anti-A, anti-D), a note, a small blood sample, and two sections of the microscope. Use the three "anti" bottles on the blood sample on the counter, then compare the results to the chart on the wall. Make a note of the names and blood type. Use the microscope parts and blood sample on the microscope to work out the code needed and enter it in the door. If you're struggling with the logic and maths, the code is: 697 956