To build a site where you do bitcoin business, be it gambling or anything else, you need the following:
- SSL Certificate to keep communication safe (gives https in address window - and communication between visitor and site is encrypted). This means password and other sensitive information does not fall in the wrong hands.
- If you plan on taking bitcoin deposits you must either run a node or have somebody run it for you, maybe some 3rd party exist that already have the infrastructure for it. Security here's very important, and you should not run the node on the same machine as your web-site. This is a bit complicated, unless you have experience doing it. Deposits and withdrawals needs to be automated preferably.
- You must run a web-server, nginx could be a better choice than apache if you plan on getting a lot of traffic.
- For hosting, a VPS or a dedicated server is your best bet.
- The game itself could be customized from an available source - if license permits - made from the ground up by you, or developed by some developer you pay to do the job. If you don't have coding skills, you need to get somebody to do it for you.
- Once everything is up and running you need to do marketing. This could be done on reddit, this forum and on other social media.
Check out the offers on this page:
https://en.bitcoin.it/wiki/Trade