This tutorial shows you how to make a "Score" variable for a game. Please note that it is slightly different to how you make a cloud score. First, make a variable named "Score". How the game works defines which find of script you will use.

Color Sensing

If you want to detect when a sprite touching a particular color, use
when gf clicked
forever
if <touching color [#0000ff]?> then
change [Score v] by (1)
end
end

If you want to decrease the score when touching a color, change change [Score v] by (1) to change [Score v] by (-1).

Sprite Sensing

To sense when touching another sprite, replace <touching color [#0000ff]?> with <touching [Sprite v]?>.

Broadcasts

To use broadcasts, use
when I receive [increase score v]
change [Score v] by (1)
when I receive [decrease score v]
change [Score v] by (-1)