Can anyone recommend a game wiki that covers all major casino games?

To be honest, I haven’t seen any wiki that does cover all the main casino games. You mostly see separate wikis for poker and slots, but even those tend to be limited. When I created mine, I found that the most efficient way was to simply link back to the best resources out there, which are Wizard of Odds for strategy, Gambling.com for the rules and descriptions, and Slots.org for the slot information. All are rich with the required information about odds, rules, and how to play. Of course, if you’re creating a site with the goal of having a complete reference for each game (like in my wiki), you’ll want to link to these great resources for all the different game categories as well. That way you are giving your readers the best information. Just keep the menus intuitive enough, so that they don’t get lost when they go from one game, say blackjack, to another, such as roulette.

This is my view:

Wizard of Odds is an excellent source that covers pretty much everything about any casino game: rules, strategies, odds, etc. If you're compiling your own wiki, it's a good place to start researching and verifying information on various games. The forum is a great way to get player input into the process as well. Make sure you use them as sources of verification.

There’s no one wiki that covers all the games in full detail either. I’ve looked at many. Some cover Blackjack and Poker well, some have basic slot descriptions. The problem is that casinos change rules and variations regularly. My suggestion is to create a wiki that includes direct links to the official rules sources of major casino websites. Include user comments from the forums like Two Plus Two or subreddits about gambling. That way you can get new information quickly. Organize the wiki by games. Each game should have its own section, with subsections for rule variations and house advantage information.