Grunty Industries is a tremendous factory-themed level, the sixth in the Nintendo 64 game, Banjo-Tooie. With five floors, a rooftop, plenty of hidden corridors, and dangerous new challenges, it is widely considered by fans to be the most difficult of Banjo-Tooie's levels.
The learned abilities are Banjo's Snooze Pack (a method for the bear to regain health), Kazooie's Leg Spring (a way for the bird to leap to higher areas), and the Claw Clamber Boots (boots that let Kazooie climb up footprints on walls to reach new areas)
Grunty Industries cannot be accessed without levitating and starting the Chuffy train in Glitter Gulch Mine, then defeating Old King Coal to earn control to the train. To enter Grunty Industries' interior, the player must activate the train switch in the dangerous moat of Grunty Industries' exterior. The player then can enter Grunty Industries through the building's train station. Different floors must be initially accessed through broken pipes and vents, something that makes Grunty Industries rather intricate to navigate.
Throughout the level are security cameras that will release mechanical attack drones when Banjo and Kazooie come into view. These cameras can be easily destroyed with grenade eggs. Also, some parts of the level require power, where Banjo must use his Taxi Pack ability to pick up batteries scattered throughout the level and power the doors to the hidden areas. Aside from the intricate puzzles, there's also nuts, bolts, washers, and disgruntled workers to damage Banjo and Kazooie throughout the level.
The game offers two minigames: one being the Twinklie collection minigame in the Packing Room, and the second being another first-person shooting stage called Clinker's Cavern (not to be confused with the original Banjo-Kazooie's Clanker's Cavern.)
Mumbo Jumbo's ability in Grunty Industries is EMP, a technique that can be used to halt electromagnetic pulse, causing machinery to stop working for a set amount of time. Humba Wumba's transformation is the Washing Machine, that along with having access to the service elevator and employee-only rooms, can shoot underwear. The Washing Machine is essential in cleaning the six "skivvy" rabbits that require their uniforms to be cleaned, which in turn earns a Jiggy.
The major boss of Grunty Industries is Weldar, a vision-impaired welding torch that can use suction to damage Banjo and Kazooie, summon minions, and electrify the floor. He resides in the Repair Depot and is rather difficult to reach, as the Repair Depot will only open after a select amount of character skills are used together. After defeating him, the bear and bird have potential access to two Jiggies.