I bought a copy of Carcosa from Geoff a little while back and started weaving in some of his rules as houserules in my ongoing Mutant Future game. In particular, I refer to his rules on variable hit points and variable damage.
I note Carcosa is principally intended for Basic D&D-driven games but lends itself to flexible adoptation in other similar systems. Speaking from my group's experience, the variable HP and damage rules worked very well and added a hightened level of tension and fun in our combats.
The thing is that Mutant Future characters determine their overall hit points by multiplying a character's Constitution attribute by a d6 or d8 depending on a character's race. What I did was ditch the d6 or d8 determined by the Mutant Future character's race and instead applied the Carcosa rule on variable dice to determine hit points through the table in page 11.
We do this before every combat.
Things did get very exciting as compared to a straightforward application of the Mutant Future rules.
I was wondering if anyone here ever tried something like this in their other games?