§12.4. Timed Input
Inform normally expects a purely turn-based game: the player acts, the story responds and waits for the player to act again.
Occasionally, however, we may want to offer a different mode of interaction, for instance with turns in which the player has limited time to come up with his next act. Likewise, we might want to have text that printed itself to the screen gradually, to represent dialogue with pauses, or the speed of a typewriter placing letters on a page.
It's best to be careful with these effects: overdone, they can be very annoying to players who prefer to read at a faster speed. Nonetheless, they do have their uses.
Inform does not have standard syntax to handle real-time delays and output, but there are several extensions that provide this capacity. Erik Temple's extension Real Time Delays, for instance, allows us to specify a delay in milliseconds before continuing with whatever aspect of the game is currently in progress.
See The Passage Of Time for ways to keep track of clock-time within the game