Finding a combination of six keys that works correctly doesn't guarantee that every combination of six keys will work. In fact, the most basic keyboard design has thousands of three-key combinations that don't work! That's a significant number, although it's still less than 5% of the total number of three-key combinations.
A quick way to identify problematic combinations is by pressing and holding ASDW (the most popular keys for movement in games) and then, while holding them down, pressing every other key one by one. If you come across a key that doesn't work, try releasing some of the ASDW keys. Chances are high that you will find a three-key combination that fails.
If your application utilizes other key combinations, make sure to test those as well!
Sometimes there are certain keys that cannot be detected by browsers. One notable example is the PRINT SCREEN key. When pressed, browsers generally cannot capture or recognize this key event.
Additionally, certain keys have a system-level behavior that takes the input focus away from the web page. For instance, pressing the Windows key on the keyboard will shift the focus to the Start menu or the desktop. To continue using the demo or interacting with the web page, you can regain focus by clicking on the demo window.
It's important to note that this demo has been developed and tested using a standard full-sized U.S. keyboard and major Windows-based browsers. The key names and layout may differ on your system, but the phenomenon of ghosting behavior will still be apparent.