The name given to a prevalent strategy in the
Worms series of games. The idea behind darksiding is to basically dig (or
blowtorch, rather) yourself in a hole, or
hide somewhere, or place your worms somewhere the enemy can't get to you, and then simply wait and/or call
Strikes. After awhile your enemy will have to come to you, and will probably
screw themselves over in the process, while you're simply waiting there,
invulnerable, for them to get down weak enough that you can come out and finish them off easily.
Darksiders are relatively rare on Wormnet, but if you run across one you're pretty much guaranteed to lose, because as much as everyone hates darksiders it's simply the best strategy to use.