Very likely, but potentially even better is this WebTiles version of Dungeon Crawl Stone Soup: http://crawl.akrasiac.org:8080/#lobby

I think you might be underestimating the complexity of nethack

Here you go: http://gateone1.rs.liftoffsoftware.com/

That's a direct link to the Gate One demo. You can play Nethack (among other things).

Here's the source to Gate One: https://github.com/liftoff/GateOne