More users are seeing icon searches within Google Now, as it appears that Google is rolling out this feature within the Google Now page to a larger group of people. This also still appears to be a staged rollout which means that not all uses are going to see these icon searches just yet, however it will be immediately noticeable if they're there as they'll be right near the very top of the page when you open up Google Now. The Icons will sit just below the search bar and will allow users a quick and easy shortcut to a particular search query just by tapping on the icon. It's also possible that these icons are showing up in certain regions only. For now though it isn't something that Google is likely sending out to everyone.
There are icons for all kinds of searches, including for jumping into a game of Solitaire, Tic Tac Toe, and more, and they seem to be categorized out into various different sections as well, although only if you tap on the "view all" button which takes you to the page of all the icon searches that are available. From the main Google Now page, you'll simply see a random collection of these icons. They will change from time to time so they won't always be the same ones you see here.
Once you tap on the view all button you can see categories for fun, weather, travel, my stuff, and others, and tapping on a particular icon should take you to the relative searches along with visible Google Now cards that are also related to that particular category or icon search, such as booking a hotel. While this doesn't seem to be a wide feature rollout at the moment, it's still one of the more recent changes that Google has been making to Google Now and the Google app. In addition to these icon searches, a recently updated version of the Google app beta suggests that Google is getting ready to add keyboard support for Google Assistant, which would allow users to type their queries to Google Assistant just like they can inside of the Allo app.