hi, i have buy the game guru, 19eur in steam, but HOW i can change the sky and the sun???
where are the menus functions???

In test game, press [Tab] twice to open the metrics panels. You can change the skybox and adjust the strength and color of the sunlight (surface light).

i mean not in test mode, but on the standalone, how to change the sky and light of the sun in the final product...

You create your game in GameGuru and set the sky , sun , terrain how you like it .....
When you create your standalone "File" ...."Create Standalone " its creates it with your settings ..

If it does not show up. Then in the standalone folder find the sky bank folder and change the name of the one called default, to 1default and try again. This is a reported issue.

@ Pirate Myke

Is there a way to change the position of the sun (IE the time of day), so the sun angle is different?

Yes there is a way and they just turned it back on, so you will need to play with it.
In the skyspec.txt file for the skybank to are working on there is this:

The biggest thing to remember is the actual skybox is rotated around the terrain, then you match the sun rotation to that position. Tricky at first and GameGuru must be restarted to reflect the changes.

;GrimmNight
;SUNLIGHT DIRECTION VECTOR
SunDirection = 50,50,100 <---- sets the rotation of the skybox texture it self. X,Z,Y
;SUNLIGHT STRENGH MULTIPLIER (DEFAULT 100)
SunStrength = 1 <------Brightness of the sun light, Default is 100
;SUN COLOR (RGB)
SunColor = 250,1,1 <----- color of the sun light
;SUN ROTATION
SunRotation = 113 <----Used to align the sunlight to a texture moon or sun spot, also controls the suns shadow direction.
;SKYSCROLL SPEED
SkyScrollX = 10 <---- the speed and direction of the moving clouds
SkyScrollZ = 10


Hope this helps out.