The best free alternative to Solitaire is Simple Solitaire Collection, which is also Open Source. If that doesn't suit you, our users have ranked more than 25 alternatives to Solitaire and many of them is free so hopefully you can find a suitable replacement. Other interesting free alternatives to Solitaire are PySolFC (Free, Open Source), AisleRiot (Free, Open Source), Solitaired (Free) and Solitaire.gg (Free).
Play Solitaire with this simple game! Currently you can play AcesUp, Canfield, Forty&Eight, FreeCell, Golf, Grandfathers Clock, Gypsy, Klondike, Mod3, Pyramid, SimpleSimon, Spider, Tripeaks, Vegas and Yukon. If you want me to add more games, please tell me.
Aisleriot (also known as Solitaire or sol) is a collection of card games which are easy to play with the aid of a mouse. The rules for the games have been coded for your pleasure in the GNOME scripting language (Scheme).
Solitaire.gg provides a huge collection of solitaire games including Klondike, FreeCell, Spider and many more. The entire collection is open-source and also playable online with just the right amount of options to configure basic settings and appearance.