Here is a place to play UnNetHack. Simply telnet to guis.es to get started

From the nethack wiki: "UnNetHack is a variant of NetHack 3.4.3, maintained by Patric Mueller and others. The main intent of this fork is to put more randomness, challenges, and fun into NetHack."

Useful links: Wiki, Keyboard Controls, PuTTY, Reddit, Beginners Guide 1, Beginners Guide 2