You can use "site:itch.io keyword" on most search engines ;-)
The search box is just not a keyword search box and it seems that many people do not understand this at first. Also, it is not clear at first sight, that you can write in the tag box and are not limited to the suggested tags there.
For those suggested tags, the search box does give those tags as results, just not the titles that have those tags directly. You have to click the "strategy" tag shown to you, after searching for strategy.