I'll add that very very long game like crawl with permadeath and without accessible and trustworthy escape means strongly discourages experimentation.
It takes several hours to win minimal course. And it might take several days to make allrunes run.
Experimenting with viable builds of allruners is insanely time consuming activity...
I like approach that was implemented in Ragnarok (Valhalla).
If I remember correctly every 10 000 turns it was possible to make permanent save, that wasn't deleted on death.
