To add to the above comments, if you want to achieve anything approaching a professional standard, you will need a team of designers and developers, each with a particular skill set. A game site is well beyond the capacity of a one-man-band.
If you scale back your objectives, say, to a simple text adventure, with static graphics that you and a handful of friends can play, that might be more realistic because you can avoid using a database and SQL. This will reduce the core skills needed to HTML, CSS and PHP, with JavaScript to add some pazzazz (though that can be added later).
You need PHP because HTML does not support arrays (or any variables for that matter). You need arrays to store user names and passwords, and the status and location of players and items in the game.
Good luck!
