Solitaire is the most popular of the two games, with about 2.7M searches every month and has more sites competing in the search results. Tic Tac Toe has 165,000 monthly searches, which is still very decent.
There’s no doubt that while providing a quicker access to these games, Google will suck the wind out of many sites and apps, which previously ranked high for these searches. Google analyzes the most researched keywords and continuously tries to provide its own answer, service or entertainment that keeps people on its domain.
The games are also available on Android, and I’m assuming on iOS although I haven’t tried it.