DCSS is highly customisable and many options can be set in your options file. Online, they are often referred to as rcfiles, while offline they are set under init.txt or settings.txt (in the settings folder).
Detailed documentation on all of crawl's options can be found in options_guide.txt.
Any online player's .rcfile can be accessed directly:
- CAO: http://crawl.akrasiac.org/rcfiles/crawl-<version>/<name>.rc (Example)
- CDO: http://crawl.develz.org/configs/<version>/<name>.rc (Example)
- CSZO: http://dobrazupa.org/rcfiles/crawl-<version>/<name>.rc (Example)