I think my choice would be to have 3 different websites each one dedicated to a specific topic: casinos, poker, and bingo.
Since these topics may be related, I could put some poker on casino site, and some casinos on poker site, but I would prefer to separate things. The case of bingo is different since I read some time ago that bingo players are not usually casino or poker players. I’m not a serious gambler, but I like casino games, I like poker, but I don’t like bingo.
Search engines may treat 3 pages the same as 3 sites, but I have to tell the search engines I’m good on each topic. In order to do that I have to exchange links with other webmasters.
I have 2 options here:
-exchange links for 3 different pages/subdomains
-exchange links for the front page
In the first case I will have to convince webmasters to exchange internal links. I don’t have much experience on that but I think most will not be very receptive to that.
In the second case, you will have to exchange links with different anchor text with different sites. In some sites you use some “casino” wording, in others “poker” and etc. For every site you exchange links targeting the casino part you’ll loose 2 exchanges, 1 for “bingo” and other for “poker” since they will not accept duplicate sites.
Apart from the link exchange, your website relevancy will suffer in some way.
If you’re starting from the beginning I would not hesitate to set up 3 different sites with some different themes. I think life will be easier.