TriPeaks offers a number of free games, including solitaire. These games are free to use online or download and install on mobile devices, although some offer in-app purchases.
In-app purchases are a popular way for app designers to make money from the applications, allowing them to offer the game for free download. In-app purchases generally give the player an added advantage in the game, such as power-ups, extra lives or in-game currency. The games are often available for play using a Flash-enabled web browser as well, for those who wish to enjoy the games without needing to download an app to a mobile device.