Hey sumair, you're not the first to express interest in a Bitcoin (or crypto, anyway) rpg game. I myself have played with two on this forum, both unfortunately met their demises right around the time I got very interested, so for the time being, am not going to invest much time in them. However, I would point you to one discussion in particular, as it seems to have brought together people like yourself (MMORPG discussion with crypto integration):
https://bitcointalk.org/index.php?topic=2190459.0

Maybe you can get in touch if you have something to contribute, or simply learn from there. From my experience, getting a game out is hard enough, getting people to keep playing harder... integrating Bitcoin is an added level of complexity.

As others have mentioned, I think the languages to start mastering for a browser-based RPG are PHP and MySql (for database). But that's just the coding aspect.

You probably also need a really good foundation for the game itself: business plan including business model, storyboard.