PHP = Personal Home Page.
Such code runs on the server. When you are on a website that is using PHP to generate its pages, this is the sort of extension you will see.
If you are not running a PHP webserver/interpreter locally, it probably isn't much of a threat.
However, if you have left the idiotic default of "hide file extensions" enabled, then "game.php" may well be "game.php.exe" in reality.
Maybe a degree of caution is a good thing... but you knew that already!
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"Striking up conversations with strangers is an autistic person's version of extreme sports."
Kamran Nazeer