Look for sites with "unblocked" in the title hosted on the Google Sites platform. These are community-driven repositories for school-friendly gaming.
Since the death of Flash, sites like logic-games or itch.io often host the web-based demo or fan-made versions of the game that function perfectly in modern browsers. How to Play the Game Effectively a dance of fire and ice unblocked games link
You only need one key (or mouse click) to play. Look for sites with "unblocked" in the title
Many developers host HTML5 versions of popular rhythm games on GitHub. These links are rarely blocked because GitHub is a professional resource. a dance of fire and ice unblocked games link
Watch the rotating planets; they tell you exactly when to hit the beat.
If you feel a delay, check the settings menu to adjust the input latency.