Hello Newgrounds, I might as well make use of this News Post thingy.
For those who are stuck on a particular section in the BackDoor game, here's a quick walkthrough from start to end. Keep in mind this doesn't cover any of the bonus/easter egg content- you'll need to find them on your own!
1. Answer the phone in the bedroom.
2. Grab the pencil from the desk at the top of the room, and the diagram from the bookcase.
3. Examine the diagram (by selecting it as the current item, then pressing 'X'), which should show that there is an X on the bottom left corner of the rug. Move to that location and press 'Z' to get the lightbulb base.
4. Use the pencil on the chest in front of the bed to open it. You'll get the bulb glass.
5. Combine the bulb glass and the lightbulb base to get a whole lightbulb. This is done by opening the inventory with 'SPACE' and selecting 'Combine'. You can then insert the bulb into the lamp above the bed. Examine the lamp again to turn it on.
6. A hidden compartment should open up behind the painting. Examine the compartment to get the Square Key, which opens the door to get out of the room.
7. Push the dark box out of the way and walk through the hallway to the stairs. A cutscene will start after you get to the living room.
8. After the cutscene, move behind the vertical couch and move it to the left. You'll see that there was a coin underneath. Pick it up.
9. You should also have a clear path to a piece of paper in the upper right corner of the room. Grab this as well.
10. Use the paper on the safe on the far right of the room. You'll get a Circle Key from the safe.
11. Walk over to the kitchen area and examine the trash bin. There's a Triangle Key here.
12. Go back upstairs and use the Triangle Key on the locked door in the hallway.
13. You'll be inside a bathroom now. Just grab the towel from the bathtub for now, then go back downstairs.
14. Use the towel on the oven in the kitchen (next to the trash bin). You'll pull out a box cutter.
15. Use the box cutter on one of the cardboard boxes near the safe. You'll get a remote for the TV.
16. Combine the coin and the TV remote to get the batteries from the remote. Then use the batteries on the thermostat at the bottom right of the living room (next to the lamp in the room).
17. Turn the setting on the thermostat 'off' to toggle the gravity for the house. You can do two things now with the lower gravity. The first of these two is moving the safe out of the way.
18. Next, go upstairs to the bathroom and move the cabinet to the left, over the crack.
19. Go back downstairs and toggle the gravity again. If you did everything correctly, a cutscene should kick in where the cabinet falls through the crack and crashes into the living room.
20. Grab the book that appears near the cabinet-table crash site.
21. Go to the door that was previously blocked with the safe, and use the Circle Key to open the door. Go downstairs to the basement.
22. There will be a bunch of lamps next to crates and other things here. You'll need to turn some of them on, and leave the rest of them off. The book is the hint for this puzzle, so 'use' the book to read the hint.
23. The solution is to turn all the lamps on except for the topmost one. Then examine the slot next to the door to insert the book into the slot. If you've done everything correctly, the door should open.
24. Move on to the next room. In here is a simple movable block puzzle. If you need help solving it, refer to the diagram below.
25. And that's pretty much it! Follow the hallway to continue to the end of the game.
Ok, fine- I'll leave one small hint for one of the pieces of easter egg content. It's near if not at the end of the game. Also what you find can be used somewhere else.