Nice micro game. I suggest (if you can cut some space for it...) to implement the concept of "stepping down" the Die (like Cortex do). It's good that if you have a skill at d6, you roll a d4 instead, when you are "hindered by hunger, injury, sickness, or circumstance". But what if you have a skill at d8 or d10? Are they "destroyed" to a humble d4 too?
This is why I suggest the "Step down" rule, briefly explaining that, when you are "hindered by hunger, injury, sickness, or circumstance", you reduce your Die to the one under it, so if you have a d10, you ned to roll a d8. Or, if you have a d8, you'll roll a d6. And, obviously, if you just have a d6, you step down to the measly d4.