Plumbob

The PlumbBob (frequently misspelled as "Plumbob" ) is used in most titles of The Sims series (including the MySims series) to identify the character selected and to which the player can give commands. It is also used to show the mood of playable Sims. The PlumbBob has become an important symbol to the franchise, and it is widely recognized by players around the world as one of the game's identities. Several game covers, logos, and special products feature PlumbBobs in their designs.

Geometric Information
The PlumbBob is displayed as a hexagonal bipyramid, making it a dodecahedron, it has 12 iscosceles triangles, 18 edges, and 8 vertices.

The Sims
In The Sims, the PlumbBob is a fairly accurate reflection of the Sim's mood. If the Sim is in a very good mood, the PlumbBob will be a bright, deep green. As the Sim's mood gets lower, the green will become paler until it becomes a sort of neutral color. A Sim in a bad mood will have a red PlumbBob, and the red will get brighter and deeper as the Sim's mood gets worse.

If the Sim has a date in Downtown or Old Town, or on Vacation Island, the date will have a small blue PlumbBob, which will reflect their mood. The deeper the blue, the better their mood. (Some of the clips in the intro movie for The Sims show a larger PlumbBob that is shaped differently from the one that appeared in the game.)

The Sims 2 and The Sims Stories
In The Sims 2, the PlumbBob is white if the Sim's aspiration bar is in platinum, which produces a very high mood regardless of the Sim's motives. Otherwise, it is bright green if the Sim's mood is high, and orange or bright red if it is low. If the Sim's mood is somewhere in between, it will be a shade of green-yellow reflecting the approximate level.

Perma-platinum can be achieved through completing the Sim's Lifetime Want if the player has University through Bon Voyage, however if the player has FreeTime perma-platinum can be reached by maximizing the lifetime aspiration bar.

In Nightlife, the members of a group in an outing or a date partner will have a small blue PlumbBob over their heads. This PlumbBob doesn't reflect their mood, however. In Open for Business, business employees have a small spherical PlumbBob over their heads, which could be green, yellow, or red depending on their mood and motives. It is important to watch the color of employees' PlumbBobs so as to know when to give them a break, otherwise they might quit.

The plumbbobToggle cheat can be used to hide the PlumbBobs, which can be useful for moviemaking or snapshots. This cheat, however, doesn't hide the small outing and employee PlumbBobs.

The Sims 3
In The Sims 3 with The Sims 3 World Adventures the PlumbBob is green if everything's right, yellow if the Sim isn't good, and red if the Sim has multiple and/or potent bad moodlet(s) or low needs. There is a new meaning of the yellow color introduced by World Adventures. It is the subject of speculation, some think it means the Sim is in an "adventurous" mood, but most think that it is just the mood between green and red, as in The Sims 2.

Contrary to initial belief, a Sim's icon background changes color depending on their need levels specifically, not their mood level, unless the mood is lower than the needs. This is for the player to actively fulfill the Sim's needs or allow the Sim to autonomously fulfill them and keep the Sim's mood elated and from shifting moods. The colors shift from the mean of each need bar, from green (Good Mood), Yellow (Not very good) to red (Bad Mood).

The Sims 3: Pets (Console)
In The Sims 3: Pets (Console), If you are in debt with your karma, these words will appear on the screen: The Almighty PlumbBob is deciding your fate.

If PlumbBob is in a bad mood he will use a random bad karma power

If PlumbBob is in a good mood, you will be spared.

Controlling device
In the The Sims 2 for PlayStation Portable storyline, (events which occur after The Sims 2) the player's Sim will encounter Dr. Dominic Newlow aka Dr. Dominion (the antagonist) who created a device that can create the "Green Diamond" to control other people including the player's Sim. The ending of the game breaks the fourth wall, as he reveals that the "Green Diamond" is a mind control device used by an "Outside Force" (player).

During normal gameplay other than the storyline, there doesn't seem to be any PlumbBob at the top of the playing Sim, but it is still controlled by the player. It seems that the player controls the Sims using the PlumbBob (selected Sims will have a PlumbBob over their heads and become controllable) which became the game mechanics until the revelation of an outside force at the end.

When the game ends, the character talks to Isaac Rossum about the "Green Diamond", but they end up agreeing that all these things about the "Outside Force" can't be true and that mad scientists can cause peoples' brains to blow up.

The PlumbBob once again assumes the role of a mind control device in The Sims 3: Showtime. Players who control a genie can take command of a Sim by ensorcelling them, causing a purple PlumbBob to appear over the targeted Sim for approximately four hours. Whether this purple PlumbBob is the source of the genie's control over the Sim or just a signal showing the genie's control over them is unclear, but due to the PlumbBob's background as a mind control device the latter is quite likely.

The Sims Social
In The Sims Social the PlumBob (in the loading screens it is spelled "PlumBob") is always green no matter what mood the Sim is in.

Trivia

 * In Spore, sometimes the PlumbBob will appear in the creatures' speech bubbles in the Tribal, Civilization, and Space Stages, as a reference to The Sims series, as they are both developed by EA.
 * Also in Spore GA, there is a stained glass window effect that has a PlumbBob clearly on it.