I made a web browser playable Rogue-like about 7 years ago.
It was the first incarnation of my Dead By Zombie game. Python and a completely homegrown engine. I later decided the hack novelty of it didn't outweigh the negatives of the inferior latency and increased complexity. So I dropped support for the web UI and rewrote it to have a conventional curses-based UI for play in a terminal. No regrets.