The major missing feature is the ability to save and restore games – or, more accurately, the saves aren't persistent between sessions. You can save and restore while playing the game but as soon as you close the browser window the saves are lost. There seem to be a couple of techniques available that might help so this is probably going to get fixed later.
The interpreter is at nitku.net/if/hugo with a small library of games. For now you can only play the games that are pre-compiled for the interpreter. Later I'll add a feature to upload your own story files.
For people interested in Hugo innards or stuck with Hugo games I've also made a .hex story file parser that can extract just about anything there is to extract from a Hugo story file: Dictionary, text bank, objects, grammar, ... It can even output the Hugo bytecode in a (slightly more) readable format. The .hex parser is at nitku.net/if/hugo/hexparser.