In Athena Crisis, games can be played in fog. When fog is enabled, each field on the map can either be visible or hidden, based on the vision radius of a player’s units. What is visible changes when the units move across the map. This is a fun mechanic as you have to play more tactically than with an open map, and sometimes you get surprised.
When you are playing as a team with others, vision gets combined - and this feature made me realize how similar it is to privacy controls in a social network such as Facebook. In Athena Crisis, you have to compute which fields are visible for each user based on their team, only show those fields, and hide everything else. In a social network, you have to compute which posts are visible based on the privacy settings of all the people in your network, and hide everything else.
A bug in either system is severe: in a social network it exposes posts to people who weren’t intended to see them; and in a video game it invalidates the whole feature. And even more so, these connections only reveal themselves after having worked on many different systems over time. At the beginning, it’s all fog.
