Mopiness of Doom was one of many episodes of Invader Zim that was left unfinished at the time of cancellation.
This episode was written by Danielle Koenig and was never fully animated, however, a fan animation by a group known as Soapy Waffles exists and can be viewed here. Additionally, some designs, including one of Zim at the end of the episode, can be viewed on Aaron Alexovich's website.
The transcript for this episode can be found here.
Having cornered Zim outside his own base, Dib attempts to overpower the Irken with a genuine Freezing Talisman. However, it turns out to be his most pathetic attempt at defeating him yet, as the device turns out to be a cheap knick-knack he bought from the wizardry store at the mall that produces feeble-looking floating rabbits. Dib expresses his disgust for the thing, but this angers the rabbits, who promptly maul the boy, allowing Zim to enter his house unopposed.
Later, a dejected Dib returns home and asks Professor Membrane if it's okay to change what he wants to do with his life, suggesting he is considering giving up being a paranormal investigator. Membrane encourages Dib to follow in his footsteps and become a scientist, as Membrane believes Dib couldn't resist the allure of real science forever. For the first time, Dib takes his father's suggestion into serious account.
In the school cafeteria the next day, Dib approaches Zim and tells him he's no longer interested in chasing him, and is going to study real science. At first, Zim is suspicious, and then victorious, as he believes he has won the battle for Earth. However, Zim is confused when he realizes Dib has ignored his shouts of triumph and left. Zim can't understand why Dib isn't responding the usual way, and trying to save Earth from him... Does this mean the human boy is serious.
Meanwhile, Dib has started work with his father, which makes Membrane proud. Dib, it turns out, is surprisingly excellent at real science, getting all his formulae correct and even sharing theories with his dad that his father himself had before. Dib tells his father that he is happy pursuing the same career as him, and regrets that he wasted all that time chasing stupid aliens. All the while, a disguised Zim is listening nearby, feeling confused and scared by these changes.
Zim goes home and addresses the whole street, challenging anyone to become his new enemy. But, as Dib is the only person who knows he is an alien, he gets no response. Everyone else thinks Zim is just a kid, and an unpopular one at that. Deflated, Zim heads back inside. He finds GIR watching TV, and discovers GIR has hidden hamburgers in the ceiling. For a moment, he is angered, but he suddenly loses the urge to yell at GIR, as he is saddened by Dib abandoning him. GIR, confused and frightened by his master's lethargy, slowly backs out of the living room.
Back at the Membrane household, Gaz finds Dib studying a microscope, and asks why her brother is no longer annoying her and watching Mysterious Mysteries on TV. Dib is quick to tell her that he's no longer interested in the paranormal, or in fighting Zim, and she is stunned. Evidently, Gaz is concerned for Dib's happiness, as she tries to tempt him back to his old ways with a Vampire Donut Special on TV. However, Dib's choices are put the test when his father passes by, congratulating him on his recent work. After much internal struggle, Dib finally settles with his dad and continues studying real science.
Over at Zim's base, Zim is clearly missing his nemesis, and has taken to lying on the couch all day eating snacks. He denies that he has lost his Invader's will, but, two minutes later, Zim has now clearly lost it. The front door is open, kids are running around, playing, doing whatever they want in his home. Zim is depressed now that he's all out of snacks, and asks despairingly why everything wants to hurt Zim? GIR is also depressed because Zim has taken control of the robot's cherished couch.
Back at Membrane labs, Dib notices Zim has been absent from Skool for weeks, and begins to miss him a lot. Suddenly, GIR bursts in, sobbing hysterically, and begs Dib to return to Zim as the two are such good friends. Dib apologizes, but explains that he has a new life now, he's not going after Zim anymore, and insists he's happy.
After GIR exits, Membrane enters and asks Dib if everything is all right. However, after seeing a mistake in one of Dib's formulas, he sees it as a cry for help. Sensing he's unhappy, the Professor asks his son to open up to him about whatever problem he is having. At first, Dib denies anything is wrong, but his father knows him too well and Dib finally opens up. He tells his father he feels empty inside, that real science bores him to death, and that what he was meant to do was catch Zim, leaving his father to bang his head on the table in despair.
Without further ado, Dib runs straight to Zim's house and enters. Zim is found lying on the couch, covered in filth, and wearing a magenta bathrobe and matching slippers. Dib tells Zim that he is back to hunting him, much to Zim's joy, afterwards, the two express their joy at being enemies again by insulting each other.
Gaz is satisfied that everything is back to normal despite that her father is crying asking himself what he did wrong. She concludes that "All is right in the world again... stupid world". After the credits, the cyborg kitten comforts Professor Membrane who wonders where he went wrong in raising Dib.
- The episode "Nuff Said" of Kid vs. Kat is similar to this cancelled episode. Much like Dib, Coop decides to let Mr. Kat provoke all the destruction he wants as a result that he's always punished and seen like a liar as reward. Coop ultimately decides to return to his crusade against Mr. Kat after a nightmare he has and by the constant pleas of his friend Dennis. Unlike Zim, however, Mr. Kat didn't regret that Coop stopped trying to defeat him, although he was a bit surprised at first.
- This episode was being worked on by a fan group called "Soapy Waffles", who were originally working to animate all of the unfinished episodes. The completed episode by Soapy Waffles was at first expected to premiere at InvaderCON II : DoomCon, but then was delayed towards Christmas 2012. On Christmas, Soapy Waffles uploaded the full episode to their YouTube channel, although some of the animation remains unfinished, either uncolored or as storyboards. Their progress can be seen on their Facebook page. As of 2021, there is no version of the episode released with fully finished animation, however the version with the unfinished animation can be viewed here.
- In Invader Zim: Enter the Florpus, a plot point is that Zim similarly becomes depressed from his mission effectively meaning nothing, though instead his depression is caused by the earth not being within the Massive's path of destruction, with Dib expressing understanding due to his father dismissing his own interests.