The world of Grumble is divided into four continents, one each in the west, south, north, and east. The people all have colorful bodies and skinny black arms and legs. Men have flat heads and women have round or pointed heads. Other strange creatures also live there, such as Purple or the Fish.
The western continent is home to Grumbletown and the Grumblecampers. The people have colored bodies with black eyes. Plants from there are brown or white with purple bark.
The southern continent is a place of magic and danger. The people there resemble Grumblecampers but with eyes that are a lighter shade of their skin color. Plants here are green with brown bark.
The island is similar to the southern continent. People here have white eyes. The plants are purple with red bark.
The northern continent is cold and densely populated. The people here form black and white pairs of corresponding shapes. They do not have mouths, and can stretch and change their bodies. Plants here are orange with brown bark.
The eastern continent is a land of science and high technology. The people who come from there have metallic skin and colored eyes. The plants are blue with green bark.
A series of mysterious whirlpools links the continents and allows for rapid travel between them.
Each continent has its own language, though they are all mutually intelligible.
Grumble uses distinct letters with spaces and punctuation, written from left to right.
Oversea consists of lines and colored circles. It has spaces but no punctuation, and is written only generally from left to right. There is a rare non-colored version that uses extra symbols instead of colors.
Monochrome has blocks that form tight lines with no spaces or punctuation. It is written from left to right.
Metalese uses flowing conjoined letters with spaces and punctuation. It is written from top to bottom.