Levels are saved as user levels, and stored in $XDG_DATA_HOME/.mamba/user_levels (i.e.
~/.local/share/.mamba/user_levels) or $APPDATA/.mamba/user_levels on Windows.

A new level can be created from one of the existing templates using "New". Level properties, such as the
name, filename and background music track can be changed using the "Edit Level Metadata" button.

The level editor has 4 modes: placing tiles, placing things, editing sprites and testing the level.

Tiles are level geography, such as floors, walls and so forth.  Things are items that the snake can eat, such as rats.
Sprites are special elements with more complex items which require extra configuration information, such as tunnels.

To place tiles and things, select the desired element and click on the map to place the tile or thing.  Deleting anything
replaces the space with a floor tile (Right click also deletes). The selection of tiles can be scrolled using the arrow buttons.

Sprites can be placed as well. Sprites require parameters. Each sprite needs a unique id tag, which can be any string
without spaces, and then additional parameters that depend on the type of sprite, usually the id of another sprite.
Sprites can be added, edited and deleted.  Look at existing maps to see how the parameters can be used.

Test mode allows you to test the level without any clock running. The snake is moved using the cursor keys, or by pressing
space, but interacts with the level as in the actual game. Space will advance the snake one step, useful for testing arrows.
Replays can be stored of progress on a run to date, which is useful for debugging levels.

Levels can be saved, and uploaded to be shared with other people. Shared levels
only become available after the levels have been curated by the Mamba team.