Churchill Solitaire - The most diabolical version of solitaire ever devised. Played by Sir Winston himself. Available via the AppStore and Google.
Ticket to Ride - Ticket to Ride is a Turn-based Strategy, Puzzle, Board, Co-op, Single, and Multiplayer video game created and published by Days of Wonder and Asmodee Digital.
Microsoft Solitaire Collection - Play Klondike, Spider, Freecell, Pyramid, and TriPeaks! Plus, Daily Challenges!
Lexica - An open source word-search game.
Treys - Like solitaire... but fun!
Quackle - Open-source word game similar to Scrabble. Features a board editor, analysis tools, and artificial intelligence that rivals the best players in the world!