The Matrix is an incredibly flexible strategy that allows you to set up a Matrix where each quadrant corresponds to a set of tasks that you define through a Smart List.
Example
So for example you can have one quadrant correspond to all tasks scheduled for today that are part of your "work" category. And another quadrant holding all tasks that are due within the next 7 days etc.
How to set up your Matrix
Creating Smart Lists
To set up your Matrix you first need to create the Smart Lists that you want to use.
Configuring each quadrant in the strategy settings
Then go to the Matrix strategy settings (cog icon).
There you will see a copy of your current Matrix. For each quadrant you need to:
Type the title by clicking the text at the top
Pick the corresponding Smart List with the picker
Select a color for your quadrant
Selecting the click behavior
If you scroll down in the strategy settings you will see that you can also configure what happens when you click a quadrant.
The current choices are:
open the full list
pick a random task from the list
show the task Marvin suggest you do next
All options will be available to you when you hover over the quadrant:
But you are deciding on the default behavior when you click the entire quadrant and not a specific button.
What do the numbers in each quadrant mean?
The big number corresponds to the number of tasks left in this quadrant and the small number is the number of projects.