RPG Game like diablo in HTML 5

short answer: yes.

Yes, but it won't be easy, quick, or something you can hack together easily or quickly.

anythings possible in programming ;) thats my theory anyway

The biggest problem with gaming in pure HTML5 is sound -- real-time rendering has been solved by canvas (both 2D and WebGL). The problem with sound is that there's no real concept of mixing sounds, and only very basic play controls (start, stop, pause, reset). You can't "instance" sound data -- in other words, you can't load one sound effect and play it over itself unless you have multiple 'sound' elements of the same sound effect (that said, the actual sound data may be instanced in the background).

Luckily, a diablo-like game seems to me like it would be fairly tolerant of minor sound latencies and also not require a huge amount of different sounds loaded at once. Things that are in the realm of possibility for HTML5's sound capabilites would include simple arcade games, card & board games, face-book style games -- most modern real-time games would be difficult (though possible, if perhaps innelegant) but a diablo-style CRPG should be reasonable if on-screen enemy counts aren't too high.

Thanks for your reply...my idea is to build something like that. I still dont have the sound problems, as i am starting.

I have a doubt, should i use sprites to animate the characters and everything that moves?...or there is a better way??..

Another thing, i think 20fps would be enough...what do you think?

Thanks again.