The series features Massmouth, a green, one-eyed alien in the employ of an intergalactic magnate, The Worm, who loves collecting unique and valuable artifacts. Massmouth is one of the men tasked with retrieving stuff for The Worm from a variety of planets, and such quests are what the original The Adventures of MassMouth consists of.
MassMouth 2, boasting a more complex storyline, sees The Worm's base attacked by mysterious invaders and The Worm kidnapped, prompting Massmouth to head out to rescue his boss. Massmouthmas is a "Christmas special" puzzle level.
The mods are designed for the game port ZDoom. (Unfortunately, the latest versions of ZDoom appear to have some compatibility problems which may make certain parts unpassable without cheats.)
Tropes featured in the entire series:
- CamelCase: The protagonist's name is sometimes spelled as "MassMouth", although at other times the author spells it simply as "Massmouth".
- Massmouth sports just one eye on top of a long eyestalk. When he appears as a bot in Skulltag (a Doom source port focused on multiplayer), one of his lines is a complaint about his lack of depth perception.
- The Worm (whose appearance is taken from Half-Life: Opposing Force's Pit Worm) also has just one eye on top of his head.
- Nintendo Hard: MassMouth 2, as well as the later parts of The Adventures of MassMouth. Oooh boy. The enemies aren't numerous, but they have a lot of health, hit really hard, all while ammo is very scarce.
- Reference Overdosed: There are a lot of direct quotes and shout-outs (for example, the Worm's employees have names like Freeman and Spock). Furthermore, many of the enemies and characters include real-life people or are taken straight out of other games, such as Half-Life, though they're given different names.
- Species Surname: Massmouth's boss is called simply The Worm and looks the part, though it might be just a nickname.
Tropes in The Adventures of Massmouth:
- Abandoned Mine: One of the levels is set in an abandoned mine on the planet Nero. It is populated with dangerous Stuka-Bats (which are the very reason the mines were abandoned).
- Artifact Collection Agency: The Worm essentially has his own Artifact Collection Agency meant to fill out his private, well, artifact collection. To that end he employs several agents to retrieve the items from across different planets, supplying them with comfortable quarters and equipment, and maintaining a spaceport for them to fly out on missions.
- Bat Out of Hell: The Stuka-Bats, which inhabit the dark mines of Nero. They are dangerous enemies which attack rapidly and let out creepy screeches which sound like raspy yelling.
- Collector of the Strange: The Worm collects strange artifacts from across the universe; they include unique lifeforms (such as the miniature demon "Mini-Baron") and ancient artifacts (such as the ancient superweapon "Eye of Mahan").
- The Full Name Adventures: The title of the series.
- Infinite Flashlight: The Zippo Lighter, used to light up the dark areas in the mine level; it can work indefinitely, although you can't use guns while using it. It's actually a replacement for the chainsaw which makes clever use of Doom's built-in Muzzle Flashlight code.
- Lost Superweapon: One of the artifacts to find is the "Eye of Mahan", created by a wizard for an ancient king. Although supposed to "take out entire legions of men", it didn't stop the kingdom from falling. It's also a subversion: for all its fame, it simply doesn't work at all, and probably never did. (You can pick it up as a weapon, but it does literally nothing.)
Tropes in Massmouth 2:
- Big Bad: The one who sent his forces to kidnap the Worm turns out to be John Romero. At the end you confront him and can kill or join him.
- Evil All Along: The Qbot, who initially offers to guide Massmouth to a getaway vehicle, but attempts to "accidentally" lead him to his death multiple times, as he's secretly working for the Big Bad.
- Got the Whole World in My Hand: One of the ending splash screens, for the ending where you kill both the Worm and Romero and take over their empires, shows Massmouth grabbing the entire galaxy.
- I Always Wanted to Say That: Trooper, after he quotes The Lord of the Rings: The Two Towers: "I come back to you now at the turn of the tide," notes that he always wanted to say that.
- Idiosyncratic Difficulty Levels:
- Missing Mission Control: Trooper helps and guides you throughout the game but is discovered by the Big Bad and—despite trying to move to a "safer broadcasting spot"—you soon see him captured and killed before your very eyes. He comes back as a Spirit Advisor, though.
- Multiple Endings: The game has six endings, depending on whether you manage to save your employer, whether you kill him at the behest of the villain, and whether you side with the villain or kill him. The author tartly noted that this makes a sequel quite impossible, as all the endings may be considered equally 'proper'.
- A Planet Named Zok: Massmouth's home planet is named "Zeeble".
- Punny Name: Professor Egnogin. (As in, "egg noggin" = "egghead".)
- Spirit Advisor: Trooper, soon after he dies, returns to you as a translucent ghost. He even refers to it as "a Star Wars thing".
- Uncanny Valley: Invoked in-universe: In one of the endings, Massmouth notes that he's creeped out by the way the Big Bad's face never seems to be facing away from him (due to the way his in-game sprites are drawn.)
- Unexplained Recovery: Linguica re-appears without explanation soon after being killed in a boss battle ("I'll kill you for killing me!"). "Doesn't anybody stay dead any more?", Massmouth ponders.
- Video Game Tutorial: MassMouth 2 has an optional tutorial which basically teaches you how to play a first-person shooter. It's a bit inexplicable why, since most, if not all players will presumably be familiar with Doom already.
- We Can Rule Together: The Big Bad attempts this on Massmouth, twice. The first time, your choice determines the next mission only, since if you agree to work for him then he decides you're too dangerous to keep alive anyway. He tries it again at the end of the game; cue Multiple Endings depending on what you do.