How do you play a game on wii without the disc?

Here's how you do it: On the Wii Menu you have the option to include many different games in the form of "channels" and all you have to do to play them is to simply go to the Wii Menu and then select whichever game you have bought and stored as one of your Wii channels. There are a wide variety of games available in what is called the Virtual Console which includes games previously released for most game consoles from a couple of generations ago like the Nintendo, Sega, Super Nintendo, Turbo-Grafx 16, Neo-Geo and others. There are also new games designed specifically for the Wii, called Wii Ware games which you can buy and download as well.