I think dark maru is just another form of kalzul if you ask me. It`s an npr (non playable race), it has really good ships with appropriate pr to match, is there only to give players really good planets and is otherwise there to break the boredom of (most) fed wars and exploration. Can also supply minerals if stephen so wills it.
The game only needs 1 NPR and that is the kalzul. If you wanted to bring in the Dark Maru, then make it playable. However, not playable to just ANYONE. Firstly, it would be playable only to people who was guard. 2nd, only guards who complete a UW would be able to play the race (this of course means that guards would have to be able to do a UW). 3rd, only guards who SUCCESSFULLY finish all the missions can do a UW. 4th, a UW by a guard would be defeated if it is defeated below some level of PR lower than, say, 10 million pr (something higher than the current UW pr standards of defeat) until a UW countdown has gone down to say, 10 hours or something. The purpose of this requirement is to make it so that guards could not complete a UW simply through the cheap explore method (but, on the flip side, not impossible either). Lastly, raise the turn and credit requirements of the two parts to make it harder for guards to do a UW in the first place (guards, after all, are known to be poor, so the added costs would be further disincentive/challange in a guard UW).
This fact alone would severely limit the number of dark marus on any server given the small number of guards and even fewer people able to successfully complete a UW (guard or otherwise). Thus, any threat of imbalance would be mitigated by the fact that there are so few dark marus around to begin with. I think the advantage over other players SHOULD BE a reward of completing a UW, and not just any UW, but a GUARD UW. It`s meant to be a spectacular achievement on top of just the achievement of a UW.
R
RagnarokOP