I'm realizing that while I can't see what my opponent is doing in dark chess, the reverse is true too. So if you'll excuse my geekiness, I'm looking at it like a cloaked Bird of Prey attacking another cloaked ship. Or if you want a less Trekkie reference, a battle between two silent running submarines in open waters.
The darkness is something you can use to hide in and launch attacks. It took me maybe a half a game to realize that standard chess strategies could actually be a hindrance and using unexpected moves that would be suicide in normal chess gives you an advantage in this chess variation.
Of course you don't completely abandon the idea of defending your forward pieces, however instead of a heavily fortified front with a well guarded supply line; a smaller team of special op's making surprise raids from the darkness and then retreating back into it would be a more apt metaphor for this version of chess. Plus, this strategy also frees more pieces to guard your king than regular chess too.
Hmm, in a way it's a chess version of poker. You're playing with only partial knowledge of the whole game, and to a limited degree can control what your opponent sees (and therefore might believe) of where your pieces are.