I tried hackslash mine, was kind of neat but got boring rather quick. There didnt seem to be much to do, I like the concept though. I am going to play around with volts in creative mode. Has anyone else played volts much?
Weevils, Myst and I set up a Voltz server a few days ago. The ICBM mod is pretty awesome (and detailed!) and Myst was really interested in the nuclear power plant stuff but... on a whim we threw in the Millenaire mod and ended up playing with that almost exclusively. After not too long we just dropped Voltz... it just didn't feel game-changing enough to really keep our attention.
YogsBox pack has that mod I think, I played with that a bit too heh. That modpack seems pretty interesting. It using an old version of MC though.