The complete solution of Maniac Mansion

Please note:

The solution is based on the American version of the game, so it is possible to find differences for the Spanish version.

Start by placing any character (other than Dave) near the letterbox on the far left of the porch screen: later in the game the bell will ring and a package will be delivered that with this character you absolutely must intercept before it is picked up by the legitimate. recipient, i.e. Ed Edison. With Dave, lift the doormat and use the key found there to enter; go through the first door, grab the flashlight, continue to the right and be ready to rush back when Edna comes upon you. You can go back to the kitchen immediately (but what happened to it?): Open the fridge and take the Pepsi, enter the door on the right, go through the dining room and, in the closet, grab the fruit juices, the empty jar and try to take the acid to develop, dropping it for a grate.
Exit the entrance and go to the far right in a sitting room (have you noticed the key on the chandelier?), Continue in this direction and you will reach a dark room: turn on the light, discovering that it is a library, locate a loose panel in bottom right, open it and take the audio cassette that you will find there. Go upstairs and head left into the painting room, appropriating the brush, the solvent and the wax fruit; exit, enter the symmetrically opposite room (that of the piano) and watch TV.
Enter the reserved area using the codes of the manual: in the first door from the left is Dr. Fred's study (in a drawer there is the diary of the comet?!?!), In the second a games room that will be more useful later. Upstairs you will meet a weepy Green Tentacle, which you will have to appease with the wax fruit and fruit juices (IN THIS ORDER). The next floor includes, from left to right: Viola and Verde's rooms, Edna's room, Ed's room, the recreation room (with attached bathroom) and a small study. In Viola's room, pick up the half dollar from the floor and go up the Green tentacle, in a depressive crisis because she can't get her music band off the ground; Grab the yellow key near the right chest and the disk on the shelf, then leave. In the recreation room, exercise with the muscle machine and in the bathroom, grab the sponge from the sink. In the study, remove the paint on the wall on the right with the solvent, revealing a door that leads to an attic with some exposed electrical cables: for now you will not be able to do anything.
Instead, go to the piano room, insert the cassette in the recorder, start it, put the record in the Victrola and start this too; at the end of the hideous sound, stop the recorder, resume the cassette and turn off the Victrola. Then insert and start this eardrum-smashing cassette in the cassette player in the sitting room, in order to drop the chandelier and take the key that was placed on it: it is the key to the prisons, essential to get out (or to let a locked friend escape). Go out to the porch, move the bush to the left and open the grate, an action that you will be able to do thanks to the gymnastics first turn.
With the help of a friend who will pull the gargoyle on the base of the entrance staircase, enter the door without handle on the ground floor; in the dark turn on the light switch, go to the left to the fuse box next to which is the silver key, which is used to open the blue door in the pantry beyond the kitchen. Use it for this purpose and stand on the edge of the pool; with another character enter the underground corridor beyond the grate under the porch you just opened. At this point, QUICKLY, use the water valve to empty the pool, take control of Dave, go down to the bottom, collect the light key and the radio, then go back up, regain control of the character near the valve and close it; it is important that you are very fast if you do not want to witness an explosive game-over (Dr. Fred in fact uses the water from the swimming pool to cool the nuclear reactor).
Fill the empty can of pool water (radioactive!), Open the gate that leads to the back of the house, lift the garage door, take the handle of the tap, use the yellow key in the trunk of the car and take the tools. Open the radio, put the batteries found in the flashlight, which, together with the tools, you will have to give to a character to be placed in the attic accessible through the hidden door in the study on the top floor. At one point in the game, Dr. Fred will turn off the power for 5-6 minutes, during which this character of your choice will have to turn on the flashlight and repair the exposed wires there with tools (if you missed the opportunity, you can send a friend to the furnace room near the underground and temporarily turn off the circuits in the fuse box: in this case, however, you will have to be VERY fast).
Place Dave in the recreation room, then let your third character ring the front door bell, which you must immediately move away from the house; when you see the sequence of Ed coming down to open, with Dave go out of the recreation room and slip into his room: at the speed of light, take the hamster, the key card back there, open the piggy bank and collect all the half dollars, then jump outside and take refuge in the study. With another character, enter Edna's room and be captured; while she is away to lock your friend in the basement, with Dave enter her room, take the small key and go up to her attic on the right; turn on the light and throw open the picture, but you still won't be able to open the safe. Go back down and get caught (to tell the truth, if you have chosen Bernard, you can have him fix the library phone with tools and have him call Edna to distract her: you can find the number in the bathroom by opening the shower curtain and filling the tub by mounting the faucet handle found in the garage).
Free yourself and your friend with the old rusty key, then go to the study; give Pepsi to the carnivorous plant and water it with the water of the swimming pool; then climb it to reach a room with a huge telescope, which can be activated with the half dollars you just bought. Twice, insert a half dollar into the slot and press the right button; look in the telescope to discover the combination written in small print under the safe. Repeat any trick to go up to Edna's attic, use the combination and take the unmarked envelope from the safe. Back on the loose (if you've been imprisoned by Edna again), go down to the kitchen; fill the jar with water and put it in the microwave bottom with the sealed bag; turn it on, wait a bit, then retrieve the envelope and open it to find a quarter (actually, you can also open the envelope directly by tearing it, but doing so will compromise one of the possible solutions of the game!). At this point, you should have already seen the sequence in which Dr. Fred plays with the coin-op 'Meteor Mess' in the arcade; go there and use the quartino, noting the highest score, which is nothing more than the combination of the door of the secret laboratory ....
At this point, we have reached the final stage: follow the solution you prefer, also based on the characters chosen.

Game Video - Introduction

Part 2

Make sure that Dave receives the intercepted package and enter Ed: while he is threatening you, give him the hamster to appease him, then his package; he will tell you that he wants to stop his father, but that he has lost his war plans somewhere. With Michael the photographer, equipped with the sponge that you will eventually take from Dave, go down to the porch outside, where you will find a roll of film to the right of the stairs; Go down the underground corridor of the water valve again and use the sponge to collect the developing acid from the puddle that Dave caused in the pantry.
Go up to the dark room (the room where the green tentacle stopped you), close the door, DO NOT turn on the light, use the sponge in the basin on the left and the roll in the latter; bring the prints thus obtained to Ed, who will declare himself ready to defend you in the attack on the secret laboratory!
With Dave, go down to the basement with the rusty key (perhaps pulling the gargoyle of the stairs with a collaborator), use the light key in the locks that bar the door next to the skeleton, then enter the highest score of the coin in the control panel of the second door. -op. Save your game and launch into the grand finale. You will be stopped by the Purple Tentacle, which will be promptly put to flight by Ed Edison; enter the door on the right, ignore Dr. Fred and your beauty, open the locker on the right and put on the anti-radiation suit; open the next door with the magnetic card.
In the comet room, lower the first lever you see making dr. Fred., Then grab the comet and exit through the door on the far right, finding yourself in the garage; open the trunk, put the comet in it and start the car with the yellow key.

Part 3

With Syd or Razor, enter the piano room with the audio cassette, insert it into the recorder, start it and play a nice piano tune; stop the recording and take the tape to the Green Tentacle, who will name you a member of the band and baptize the tape as the group's 'demo'. Insert this demo in the envelope, attach the parcel stamps on it (they are obtained by trying to open it), go up to the study and use the envelope in the typewriter, placing the address of the publishing house seen on TV (if you have seen it with Dave, look at it now). Get off at the mailbox, close the envelope inside and raise the flag; go back to the house and wait a bit.
A sequence will warn you of the appreciation of the city bosses and you will receive, also in the mailbox, a music contract (the bell will ring), which you will have to bring to the Green Tentacle. With Dave, go down to the basement with the rusty key (perhaps pulling the gargoyle of the stairs with a collaborator), use the light key in the locks that bar the door next to the skeleton, then enter the highest score of the coin in the control panel of the second door. -op. Save your game and launch into the grand finale. You will be stopped by the Purple Tentacle, which will be promptly put to flight by the Green Tentacle, now your friend for life; enter the door on the right, ignore Dr. Fred and your beauty, open the locker on the right and put on the anti-radiation suit; open the next door with the magnetic card.
In the comet room, lower the first lever you see making dr. Fred., Then grab the comet and exit through the door on the far right, finding yourself in the garage; open the trunk, put the comet in it and start the car with the yellow key.

Part 4

With Bernard and the tools, go down to the sitting room with the broken chandelier, open the old radio and take the valve. Go up to the room of the Purple Tentacle and mount the valve in the special housing; read the space police poster and turn on the radio. Take Dave to the basement with the rusty key (maybe pulling the gargoyle of the stairs with a collaborator), use the light key in the locks that bar the door next to the skeleton, then enter in the control panel of the second door the highest score of the coin-op .
Make sure that the other doors leading to the basement are also open (the house one, the one open with the gargoyle, the furnace one), then regain control of Bernard, making him call the space police as often as you read on the poster. Once this is done, with Dave wait for the policeman to arrive and take away the comet, collect his badge, save your game and enter; show the badge to the Purple Tentacle scaring him to death, enter the door on the right, ignore Dr. Fred and your beauty, open the locker on the right and put on the anti-radiation suit; open the next door with the magnetic card. In the Comet Room, pull down the first lever you see to finish one of Lucas' most messed up adventures.