Kairosoft offers several "Free-to-Play" titles that are supported by in-game ads or microtransactions. While these are mobile-first, they can be played on PC via official emulators or the Google Play Games app.
However, “free download” does not always mean “pirated.” There are three legal avenues to play Kairosoft games on PC for free (or nearly free): Kairosoft Games For Pc Free Download