Used by the routine at GAME_FRAME.

Reads and clears the two event bytes (+F). A step is a click; a bad fall, "NASTY FALL !" or "HELP! I FELL!"; blown up, energy to 0 with "SILLY! YOU BLEW YOURSELF UP !" or "HOW COULD YOU ?"; bitten, an energy point off with "BITTEN!" or "THEY GOT ME", or when it reaches 0, "EATEN ALIVE" or "IVE BEEN EATEN ALIVE". All seen in play. A bad fall returns early from here, and PLAY_SCRIPT loads its script number into D, which held the other person's event, so whatever else happened to either of them that frame -- a bite, a blast -- is lost (tested in a simulator and in the emulator by writing both event bytes).