My own attempt at a hard mode:
Glacier with 2 sinister biomes. Promise of a magma pocket. No liquid water. Only brought 5 dogs, 1 crossbow and some bolts, and the rest is food and non-fighting stuff.
First frame of the game i have a pack of 8 ice wolves engaging my people. All the dogs died, the civvie with the crossbow didn't have the calm to pick up bolts so he hammered the wolves to death. Lost 4 dwarves.
Loading that starting save again, i have managed a start where i lose only 2 dogs and get only light wounds on the dwarves. It seems the better approach is to recruit the dwarves after the dogs are on the wolves, but before the dogs are dead. Tricky.
Absolutelly no water. I start digging around a big block of ice to drop a few z levels. It is a mighty operation that took 2 years. It is 4 z-levels of ice, 9x9 in size, dropping 9 z-levels. I even went to the trouble of building a roof over it. And when it drops, it barely melts, i get 1 z-level of liquid water and that's it, the rest is still ice. I quickly build my farm near where that liquid water ended and pump it over the rock. We have muddy rock and we may yet live! Unfortunatelly, that consumed all the little liquid water i made with the ice drop.
After much digging i had yet to find any metal. I finally found copper and a tiny bit of hematite. The magma pocket is quite small and i fear that if i fill up a hot bed 1 z-level below another ice cube, i won't have magma to power the buildings.
On the bright side, there are 2000 ice wolf bone bolts on our stocks. I am at 28 dwarves (was at 28 when i built the farm!), 8 of them are military. Once i was able to have them armed and ready, the ice wolves have been manageable. In the first year, i could only go out when the caravans would clear them up.