Critter-TEK (subtitle: Giant Robot Combat in a Universe Gone Fuzzy) is a parody of the BattleTech game and universe, transforming the setting into a futuristic baseball league spoof with toon-style animals and vehicles.
The rules are nearly identical to classic BattleTech, 2nd Edition; the blank record sheed in the back of the book actually is a BattleTech record sheet (complete with FASA's original line at the bottom stating that BattleTech is a registered trademark of theirs), with bunny ears drawn on the 'Mech.
 From the back cover
Greetings, oh player of Giant Robot Games. Please ignore the above meanderings. Life is tough as an Allstar Umpire, and sometimes I get carried away.
Please enjoy the following rules for playing Critter-TEK. You too can be one of the elite of the Infield Franchises, the TEKwarrior. Striding about the battlefield your giant robotic TEK, crushing all resistance before you. The TEKwarriors are the best of the best, with their Big League-style equipment and spiffy uniforms. The highest noble of a franchise is nothing if they are not a battle-proven TEKwarrior. Did I ever tell you that I wanted to be a TEKwarrior, but this bad leg washed me out of the Spring Training. Never mind.
From our Allstar view atop the Mound in the center of the stadium of the universe, you will be given a detailled view of the Five Major Franchise Houses, the TEKwarriors that fight for them, and the Feared and Respected Free Agents they employ in their quest to win the Fourth Minor League Playoff.
Critter-TEK comes complete with all the "hauntingly familiar" rules necessary to engage in Giant Robot Combat, a little role playing, and lots and lots of explosions. A sense of humor is a must, and knowledge of FASA's BATTLETECH, Major League Baseball, and Funny Animals wouldn't hurt.
Critter-TEK is guaranteed to make you more desirable to the opposite sex, lose weight, and get a higher paying job. Or maybe just waste a few hours when you're supposed to be doing something else. So sit back, relax, and try not to bust a gut. That would hurt!
Critter-TEK is an amalgam of various BattleTech products. It provides boardgame rules which are almost identical to BattleTech (board game), including Flyer-TEK (the equivalent to AeroTech), Burrow-TEK (the equivalent to CityTech rules for infantry and vehicles) and TEK-Warrior (an abridged character development system reminiscent of the MechWarrior role-playing game).
In accordance with the toon style, the level of graphic violence is notably higher than in the original BattleTech.
 The Universe
In Critter-TEK, the "Infield Franchises have been stomping each other ever since Krewzinski led the Big League All Stars out On Strike". The Franchises and other factions are described as follows:
- House Deviant (The Amphibian Suns)
- Frogs. Heisa Deviant is the Owner and General Manager. Perpetual winners who recently improved their roster through trades with House Katzen. Would have received the Big League Pennant already if AllStar had not curbed them under the pretense of neutral radio coverage of games. Notable for the New Ethan Better Buffonic Institute of Superior History (NEBBISH) where trading cards stolen from House Purina are being researched, in hopes of re-learning "How to throw Killer Curveballs" from Particle Pitching Cannons.
- House Purina (The Draconian Combine)
- Rabbits. Followers of the Code of Rabbito under Tokojointo Purina. Although Rabbits are presumed to be naturally superior, other races exist within the Combine. One example is Field Manager Georgi Timooshenko (a Bull). A special Purina combat maneuver is "Death from Below", where a TEKwarrior launches his vehicle into an enemy as a desperate last-ditch effort.
- House Low (The Conniptian Confederation)
- Mice. Led by Maximum Low, who cannot make reservations for dinner without bribing somebody. He has managed to outsmart himself on a regular basis for years, making his team the least lucky. Their special combat maneuver is the "Low Blow", aiming at the... umm... head.
- House Mongrel (The Flea Worlds League)
- Dogs. Ownership held by over 700 investors, with Jaundice Mongrel a powerful part-owner. They have some real bulls in the bullpen, but found more ways to blow it by July than any other team. Prone to clubhouse infighting. Promising breeds include the Frontier League AndErUm Rebels and the Kennel League Ornamente. Mongrel recently agreed to co-operate with Purina and Low in the Concord of Kompost.
Tonsillitis Mongrel, sixth pub of the eigth litter sired by Jaundice, became notable as he went to call games on the Big League Radio Network under contract to AllStar.
- House Katzen (The Feline Commonwealth)
- Cats. Narcon Katarina, the franchise owner, has a really cushy daughter named Meowlissa who wants mouse for dinner, and froggy is going to get it for her. Their Field Marshall has not ordered a planned offensive in 20 years. Their standard combat technique is to stand in the field, catch everything, and throw it back. Great defense, but a lousy way to advance.
- AllStar (The Blessed Order of Roselle)
- Control the MLB Statistical Computer which records all individual and Franchise statistics. And they certainly have no agenda of their own, with all the money they are making from The Big League Radio Network. Don't tell anyone they are trying to dig up Big League secrets like catcher's armor and aluminium bats, and make sure you look surprised when they reveal their secret army.
- Bleacher Bums and Foul Territory
- Rotten guys, like King Overweight of Overbite, the PRESTONE-Pirate, or the evil Redjac!-Redjac!-Redjac!-Redjac! (shut up!). And a few nice persons like Killya Cylently, the Magpie of Fallopus with her all-girlcritter team.
- Free Agents
- Wolf's Baboons under Hymie Wolf, who count the Feared and Respected Natasha Immenski with her Black Hippo Comany and the near-invincible Mastodon Battalion among their roster. Their special rules include "Seventh Kangaroo Sneak Attack" and "The Scriptwriter Is On Their Side".
- The Swell Hounds, who never lose unless they have to because of their not-so-benevolent scriptwriter. Their special rules include "The Amazing Ghost TEK" and "The Scriptwriter Is On THEIR Side" (which works just like for Wolf's Baboons, only differently).
 Fourth Minor Playoff Update
Combining aspects from BattleTech's Fourth Succession War and the 20 Year Update sourcebook, this short section describes how House Low was swept in a five game series, giving rise to the St. Hives League (AA). AllStar also upgraded the Wrasslehog Republic's Mud-Wallow League (AA) to a (AAA) Minor League Expansion Franchise, scheduled games against Deviant and Purina and then sent AllStar lineups to buffer the Wrasslehog roster.
 Arrival of the Crans
The descendants of Krewzinski return to the Infield as several Franchises calling themselves "Crans", with Big League equipment, Aluminium Bats and radiators full of PRESTONE. They throw a lot of breaking balls, tend to play for one run at a time and almost never steal bases. And they hate each other as much as they hate the Infield.
 TEK Building
The construction rules are almost identical to BattleTech, although components have different names and working principles (e.g. hamster wheels for engines, coil springs instead of jump jets, and fireworks for missiles; similarly, giant matches replace Inferno launchers and giant banana peels replace mines under BurrowTEK).
 Classic Games Play-By-Play
A scenario section including
- "Raid on Prestone Wells" (Bleacher Bums under King Overweight vs. Col. Leon "Leap" Frogg of House Deviant on Prestone Wells)
- "Hippos against the Combine" (Natasha Immenski's Black Hippos vs. House Purina's Second Bat of Light on Ramalamadingdong)
- "Alley League AllStars" (House Katzen defending the Really Defiant Industries of Hesperesperus II against a Purina raid)
- "The Malt Liquor War" (Two lineups of House Low's Rodent Regulars counterattack against House Deviant's 8th Citrus Frogiliers, 1st Crisis Lanciers, and others on St. Hives)
- "The Mad Mongrel" campaign (Androgynous Mongrel rises up against his sibling Jaundice and their troops fight on Caramello VI)
- "The Battle at Misery Stadium" (Wolf's Baboons are deployed on Misery with about a zillion bunnies poised to kill them)
 Critter-TEK Big League TEK-nology TEK Readout 5150
This section provides TEKs, most of which clearly resemble well-known BattleMechs, usually with identical game stats and complete with battle histories and notable TEKwarriors:
- RUN-1T Cottontail (Locust)
- SNY-3R Snyder (Spider)
- MKY-MO UrbanMouse (UrbanMech)
- JCK-9R Jack (Panther)
- WRM-2S Wormies II (Hermes II)
- CEC-1L Fielderman (broadly equivalent to the Hatchetman or Axman but a different design with a mass of 90 and two assault ACs; wields a Powerized Slugger)
- ENF-4GR Enfrogger (Enforcer)
- LUN-4B LunchBack (Hunchback)
- TBK-5B Trenchbucket (Trebuchet)
- D0-BRMN Doberman (Wolverine)
- JUN-10R Griffey (Griffin)
- DAV-1S Dodgerman (Rifleman equivalent, but a different design with two PPCs)
- TDR-5B Thunderbunny (Thunderbolt)
- 1-DRB-01 Hobbes (Archer)
- H1-PP0 Whamhammer (Warhammer)
- MAF-3R Mafrogger (Marauder)
- PKD-1M Pachyderm (Awesome)
- MND-0ZA Shortstop Special (Charger)
- BUN-1R Bunnymaster (Battlemaster)
- ARN-1D Schvartsenegger (Atlas)
While obviously heavily inspired by BattleTech and produced under a valid license from FASA, Critter-TEK is not a BattleTech product itself. It was never meant to contribute canon to the BattleTech universe.