Maniac Mansion 2: Day of the Tentacle

Purple Tentacle, one of the crazy Dr. Fred's creations, drinks contaminated water from Dr. Fred's Sludge-o-matic. He mutates into an insane genius and grows arms, and now he's plotting to take over the world. In an effort to stop him, Dr. Fred sends three friends, Bernard, Hoagie and Laverne back in time to yesterday, in order for them to turn off the Sludge-o-matic and stop the sludge from spilling into the river, thus preventing the whole incident. Naturally, the cheap doctor uses a fake diamond over a real one in his time machine, which blows up sending Hoagie 200 years into the past and Laverne 200 years into the future.

Now you must bring back Hoagie and Laverne, with the help of the time machine's ability to move objects between time periods, and then stop evil Purple from taking over the world.