Starting with Chrome version 66, Google has introduced auto-lock for all video clips inserted into webpages and set with autoplay mode. But the company did not anticipate the impact of this change on numerous online gaming sites and pages that use sound in a completely harmless way to complement the visual experience offered to users.
Back in revision 66.0.3359.181, the Chrome PC version temporarily stops automatic audio blocking, but only for websites that use the Audio Audio API for sound playback, not those using HTML tags. The concession is only intended to allow webmasters to make the necessary changes to comply with the new rules imposed by Google, such as setting up games and videos with sound off, so users can manually start the sound if they want to do so.
That's why Google will automatically switch back to Web pages, starting with Chrome 70, expected to launch in October.
The bad news is that many of the web browser games in circulation are pretty old, updating them to meet the new Google criteria is unlikely.