Since portals try to appeal broadly, the game areas should include a representative sample of the most common games, e.g. card games, board games, and classic arcade games. For legal reasons some games cannot be copied exactly. Note that you can customize generic games by changing the graphics without changing the rules. For instance, Las Vegas casinos spice up generic gambling games by placing them in exotic themed environments. Income from the game itself .
Some advertising actually pays for itself.
For instance, a branded game can also support advertising. The key to pay for play is to offer something you can't get for free elsewhere, such as cash prizes, persistent worlds, or community. The flip side of placing a game on your web site is to place your product within in a game. Just as Nike pays athletes to wear their shoes, so many companies pay game publishers to have their products featured in games. Of course the games should be appropriate to the product and feature it in a positive light.