It is a common complaint among a lot of experienced DCSS players that the game is too long. I have 10 wins under my belt and I stopped playing mostly for this reason. About half way through the game your victory is essentially guaranteed.
I disagree about the early game though, this is the most exciting part of DCSS, and the hardest.
> contracted to twenty-seven levels
For anyone unfamiliar, 27 is a number ingrained deeply into the game, with some traces very well hidden.
https://www.reddit.com/r/dcss/comments/mvrc1w/did_anyone_of_...
https://github.com/b-crawl/bcrawl seems to make the game shorter and be fairly active.
My chief lingering complaint with crawl is that the game is too long. Early game is tedious and last I played seriously the midgame tended to drag on. I'd like to see the standard game contracted to twenty-seven levels. Squeeze down Orc, Lair, the Lair branches and so on.