To increase the variety of builds and overall interest in the game, each source brings a varying number of points, which depends on a number of factors. Mainly, this number depends on boundary values: Power and Combo. For simplicity, let’s assume they grow linearly. Each acquired upgrade simply increases Pow or Cmb by a certain constant. Range of points you can get lies between Pow and Pow+Cmb.
It would be more accurate to consider the stars modifier:
[Pow × src_pow_mod : Pow × src_pow_mod + Cmb × src_cmb_mod × (1 + Stars%)].
Each activation of a source (mouse click, key press) increases its current combo level by a small value. But what kind of combo is it if you can’t break it? It is the activation of alternative sources that is responsible for reducing combo. To make the builds even more interesting, the speed of combo reduction and growth can also be affected. Maintenance is responsible for both of these values. Growth of combo is quite simple, it always increases by Mnt multiplied by a certain constant. The fall of a combo is a bit more complicated. Activating an alternate source will subtract your Pow from the current combo level minus the Mnt source you are subtracting. So if, say, Pow of mouse is below Mnt of idling, mouse clicks will not affect the waiting combo, it will continue to grow every second.
So that life is not a fairy tale, Cmb of the source has a negative effect on its own Mnt. The higher the combo, the harder it is to hold. Does it make sense? It does.
Actually, it is already quite a difficult math to just keep it in your head, so for your convenience, you can look up all important information by pointing the cursor at the source:
Pow already added with Pow star bonus, Cmb added with Pow and multiplied by star bonus, Cmb is deducted from Mnt (so it is negative on screenshot above). So when you look at Pow and Mnt from two different sources, you can understand stability of the combo.
And what is that grey thing on the right?
Oh, you are very attentive. The fourth source is pluses. They also participate in the combo system, but in a different way. Their combo is raised by collecting plus points on the board (10% for each) and falls for collecting everything else but dice (by a third of max value).
As you can see, the hint of their Pow is given as a percentage. This is because they give you an extra percentage bonus, which is added to the acquired cell bonus. Grey pluses give 15%, yellow give 35%. Bonus is added to this percentage. As we can assume, their combo range is also not fixed and can be increased. Both the lower and upper limits of the combo are increased by collecting the yellow pluses.
Presumably, you have already came up with a plan to conquer the world with yellow pluses with a bonus of 100500%. Yes, it is possible. But the growth of Pow and Cmb for them is logarithmic (with base 2). Anticipating another question, I can immediately answer: yes, yellow stars affect this combo too.