The mechanic that I found the most interesting in Ocarina of Time while playing was the day/night cycle that triggers when the player enters certain non-narrative linked areas and the ways this was used to add and alter the content of the game in ways that add depth to the game in a remarkably impressive way for such an early implementation of the mechanic. Searching for some discussion on day/night mechanics in games I stumbled across this reddit thread in the large (700k+ subscriber) /r/gaming subreddit about day/night mechanics in games (https://www.reddit.com/r/Games/comments/24igkc/weekly_rgames_mechanic_discussion_daynight_cycle/). Nintendo games were some of the most frequently referenced in the thread, Zelda and Pokemon being the main two series. Because these were the earliest games referenced in the thread to my knowledge, I was interested in the history of day/night mechanics in games. This led me to this DigitalPress forum thread from 2006 on the subject (http://forum.digitpress.com/forum/showthread.php?89524-First-game-with-a-day-night-cycle). Despite some uncertainty, it seems that the game Red Alert from 1981 is the earliest game mentioned with a day/night mechanic and in-game clock that changes as the player progresses through the game (video of gameplay: https://www.youtube.com/watch?v=4iHMzi86KuE). Many games use the in-game clock or day/night mechanic to add difficulty during the night-time, with Minecraft being the most notable modern example of this that comes to my mind. In Minecraft the player must try to gather enough resources, weapons, and/or shelter in order to survive the flood of monsters that come when the sun sets. The nighttime and darkness in the game is something the player grows to fear almost as much as the sound of a Creeper about to explode. This seems to be a fairly common experience with day/night mechanics in video games as noted by many of the posters in both threads. Ocarina of Time eschews the notion that the night has to be a bad thing in the game, offering certain night-time-only opportunities to the player like the grave-digging minigame in Kakariko Village.