A few times I was asked if I knew how to do those double jumps in games. It is not that hard to program. All you need is to have a extra boolean that sees if you are not double jumping and trigger the double jump while in a regular jump. See the code.
' Doublejump and jumping example Import mojo Global px:Float = 320 Global py:Float = 240 Global playerjump:Bool = False Global pincy:Float = 0 Global doublejump:Bool = False Class MyGame Extends App Method OnCreate() SetUpdateRate(60) End Method OnUpdate() ' If the player is on the ground and the space bar is pressed If playerjump = False And KeyDown(KEY_SPACE) = True pincy = -3 playerjump = True End 'Double jump If playerjump = True And doublejump = False If KeyDown(KEY_SPACE) If pincy < 0 And pincy >-2.0 pincy = -3 doublejump = True End If End If End If 'If the player is in the jump If playerjump = True pincy += 0.1 'if the player is going up If pincy <=0 For Local i:Int = 0 Until Abs(pincy) py -= 1 End End ' if the player if going down If pincy > 0 For Local i:Int = 0 Until pincy py += 1 'if the player touches the ground If py > 240 Then playerjump = False doublejump = False py = 240 Exit End End End End End Method OnRender() Cls(0,0,0) SetColor(255,255,255) DrawRect px,py,32,32 DrawText "Press space bar to jump. Press space again in jump to double jump.",10,10 If doublejump = True DrawText "Doublejump",px+16,py-10,0.5 End If End End Function Main() New MyGame() End