Maniac Mansion

Reset game:
In the Japanese version, enter RESET as a password.

Hidden message:
In the Japanese version, enter JALECO as a password.

View credits:
In the Japanese version, enter the following characters at the password screen. Press Right(4) and enter the highlighted Japanese character. Press Right then Down(2) and enter the highlighted Japanese character. Press Up then Right and enter the highlighted Japanese character. Press Right then Down and enter the highlighted Japanese character. Press Left(5) then Down(4) and enter the highlighted Japanese character. Press Up(3) then Left and enter the highlighted Japanese character. Press Up(3) then Right and enter the highlighted Japanese character. Enter spaces to move to the second line of the password. To do so, press Right(4) then Up and select that option to enter spaces. Once at the second line, repeat the process to enter the same Japanese characters again. Then enter spaces to go to the third line of the password. Enter the same Japanese characters again. Then select the bottom right button to accept the password.

Sound test:
In the Japanese version, enter the following characters at the password screen. Press Left and enter the highlighted Japanese character. Press Right(2) and enter the highlighted Japanese character. Press Right(3) and enter the highlighted Japanese character. Press Down(3) and enter the highlighted Japanese character. Press Up(2) then Left(3) and enter the highlighted Japanese character. Enter the same Japanese character again. Press Down(2) then Left and enter the Japanese character. Press Up(3) then Right and enter the highlighted Japanese character. Press Down(4) then Left and enter the highlighted Japanese character. Press Up(4) and enter the highlighted Japanese character. Then select the bottom right option to accept the password.

Hint: Skip the arcade part:
You do not have to do anything with the arcades. If you do not fix them, the combination will always be 0000.
Information in this section was contributed by Kcalblabelsk8r31.

Hint: Own two hamsters:
Have Sid or Razor put the hamster in the microwave. Turn it on and while it is on, execute the "Get Hamster" command. You will have the hamster, and when you open the microwave the blown up hamster will be there.
Information in this section was contributed by Kcalblabelsk8r31.

Hint: Get past Nurse Edna:
If you are quick, you can go in Edna's room, and select the top of the ladder. You will go past her and outrun her into the attic room.
Information in this section was contributed by Kcalblabelsk8r31.

Hint: Get Nurse Edna out of the kitchen quicker:
At the beginning of the game when Edna is in the kitchen, carefully walk until she sees you, then run out of the kitchen. However, you must be quick about it. You can then re-enter the kitchen and she will not be there.
Information in this section was contributed by Zac.

Hint: Run up Nurse Edna's water bill:
Turn the faucets in the kitchen and bathroom on and waste water.
Information in this section was contributed by Zac.

Hint: Get Weird Ed to like you:
Get his package when it arrives before he does. Then, take it up to his room and give it to him. You can then enter his room as you please, and he will not throw you in the dungeon. However, do not take anything while he is in there or he will not like you anymore. You can also take his hamster when he is not in the room and give it back to him. Note: Edna will never like you.
Information in this section was contributed by Zac.

Hint: Feed Meteor to Plant:
Execute the "Use Yellow Key" command in the car before you get the Meteor. Then, get the Meteor and run all the way to the room with the Plant. Feed it to him. The fence will be blown up.
Information in this section was contributed by Kcalblabelsk8r31.

Hint: Messing with the publishers:
Send them the original manuscript, the black tape, the tape with the record recorded on it, the tape with the broken record recorded on it, the record, the broken record, an empty envelope, or the envelope with the quarter still in it and see what they say.
Information in this section was contributed by Kcalblabelsk8r31.

Hint: Do not lose any items when getting past Green Tentacle:
Early in the game, when you first go to the third floor, Green Tentacle will be there saying that you cannot pass unless you give him food. Give him the can of Pepsi. He will say, "Twelve full ounces, that's a lot. Thanks kid." Leave the room. Return, and he will be gone. You will still have the can of Pepsi.
Information in this section was contributed by Kcalblabelsk8r31.

Hint: Get past Purple Tentacle:
Give the Purple Tentacle the Meteor Police Badge after you call him and he arrives. He will drop his badge.
Information in this section was contributed by Zac.

Hint: Opening the garage door and grating:
To open the garage door and the grating in the front of the house, use the Hunk-O-Matic machine by the bathroom twice.
Information in this section was contributed by Zac.

Hint: Break out of the dungeon:
In the dungeon, move your pointer around the wall. There will be a loose brick somewhere. Push the loose brick and the door will open.
Information in this section was contributed by Kcalblabelsk8r31.

Hint Keys:
Information in this section was contributed by Zac.

The "Silver Key" opens the swimming pool door.
The "Yellow Key" starts the car and opens the trunk.
The "Old Rusty Key" opens the dungeon door.
The "Card Key" opens the door to get to the meteor.
The "Key" opens the front door.

Hint: Quicker game:
At the beginning of the game, have someone (Dave recommended) get caught by Edna. Keep him in here to use the lose brick every time someone gets stuck in the dungeon. By doing this, you will not need the old rusty key.
Information in this section was contributed by Kcalblabelsk8r31.

Hint: Ways to die:
Note: This trick only works with Razor. Get the Hamster from Weird Ed's room and put it in the microwave. Close the microwave and turn it on. Take the remains of the Hamster and give it back to Weird Ed. He will be so mad that you killed his hamster that he will kill you.
Information in this section was contributed by Tim Williams.

Have Sid or Razor's demo tape published and give it to Green Tentacle.
Information in this section was contributed by Kcalblabelsk8r31.

Drain the pool. Have someone go in it. Leave them in there.
Information in this section was contributed by Kcalblabelsk8r31.

Use the glass jar on the pool. Use the glass jar in the microwave. Turn on the microwave. When it is done, open the microwave and you will die of radiation.
Information in this section was contributed by Kcalblabelsk8r31.

Hint: Blow up the house:
Drain the pool and push the red button at the bottom of it. You and the two other kids will die as well.
Information in this section was contributed by Zac.

Hint: Sad ending:
Kill Dave then complete the game. Sandy will not see her boy friend at the end.
Information in this section was contributed by Kcalblabelsk8r31.

Hint: Funny ending:
Retype the manuscript and get it published. Give it to the Meteor. He says "I don't have to be evil anymore". He becomes a writer and you will see him on a talk show.
Information in this section was contributed by Kcalblabelsk8r31.

Hint: Zombie ending:
Kill all three of your characters. Do not do anything to cause a meltdown, but kill them off individually. The game will say that Meteor took over the world, and Sandy became a Zombie.
Information in this section was contributed by Kcalblabelsk8r31.

Glitch: Invisible character:
Blow up the hamster and give it to Weird Ed. He will kill you. You can still use that character, but he or she is invisible. If your do this, all their items will be erased.
Information in this section was contributed by Kcalblabelsk8r31.

Glitch: Walk past the Green Tentacle on the third floor landing without feeding him:
Play as any character except for Bernard (he will run away from the Green Tentacle in fear). Walk up to the Green Tentacle on the third floor landing and get as close as possible to him. Select the "New Kid" action and choose either of your other two kids. Next, select "New Kid" again and go back to your character who is with the Green Tentacle. As soon as the room appears on the screen, walk your character past the Green Tentacle and up the stairs to the left. "OOMPH!" will appear in the dialog area at the top of the screen as you walk past him. Do not stop moving or your character will automatically walk back to the right side of the tentacle. If you do this early enough in the game, Nurse Edna will not be in her room because she will still be in the kitchen. You can quickly take the small key from her night stand. If you do decide to enter her room, be careful because she will walk through the door after a few moments, especially if you go up the ladder into her attic. Also, Weird Ed's package will arrive much earlier in the game than usual.
Information in this section was contributed by Jeff Behnke.