Even today, HTML5 games won't function properly across all modern browsers without using Flash via soundmanager2.js as a crutch to get around unacceptably poor audio tag implementations.

In particular, the audio tag implementation in Safari makes pure HTML5 games range from annoying to unplayable, because there is a completely unavoidable 500 +/- 1000 ms delay between calling play() and the audio actually playing through the speakers.

This game is from 2011.