From a terraining perspective, if this is meant to be a playable area, it is too dark. You could tune the lights to something darker than day light, but still be able to clearly see units and stuff. If you cannot clearly see, this is a gameplay problem. As a comparaison, remember the "Left to die" map with day/night cycle, well you get the feeling that it's night, but you still clearly see.
They made a forest with 200 trees, and then they made the same one with half and it looks almost the same. You get the same feeling of forest without having to use that many trees. Same goes with lighting, but for visual ease, you don't have to make the screen black to show people that they are in a cave. If the terrain is well made and the lighting is just enough "darker than usual" they will understand.
You could use different techniques to amplify the idea of beeing in a cave such as DrSuperEvil suggestion to attach lights to some units which will show the player the different between what is bright and the rest of the map beeing darker.
You could make the camera slightly closer to unit, just like if it had to be "in" the cave with the units.
You could make the map with a black mask instead of grey one so the top of the cliffs are not revealed when passing nearby.
You could do terraining to add glowing stuff like, burning stuff that lights the paths... maybe it's a special building that scv build that are kind of firecamps or light spots so you can see along the ways...
But in the end, that lighting to me is too dark. It's very hard to see anything.
Seems like my post was flagged as spam, probably because of the external link... at least now you can see my points.
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From a terraining perspective, if this is meant to be a playable area, it is too dark. You could tune the lights to something darker than day light, but still be able to clearly see units and stuff. If you cannot clearly see, this is a gameplay problem. As a comparaison, remember the "Left to die" map with day/night cycle, well you get the feeling that it's night, but you still clearly see.
It's similar to blizzard's tip about doodads here: http://us.battle.net/sc2/en/blog/20097658
They made a forest with 200 trees, and then they made the same one with half and it looks almost the same. You get the same feeling of forest without having to use that many trees. Same goes with lighting, but for visual ease, you don't have to make the screen black to show people that they are in a cave. If the terrain is well made and the lighting is just enough "darker than usual" they will understand.
You could use different techniques to amplify the idea of beeing in a cave such as DrSuperEvil suggestion to attach lights to some units which will show the player the different between what is bright and the rest of the map beeing darker.
You could make the camera slightly closer to unit, just like if it had to be "in" the cave with the units.
You could make the map with a black mask instead of grey one so the top of the cliffs are not revealed when passing nearby.
You could do terraining to add glowing stuff like, burning stuff that lights the paths... maybe it's a special building that scv build that are kind of firecamps or light spots so you can see along the ways...
But in the end, that lighting to me is too dark. It's very hard to see anything.
Working on projects: