Coffin lock is a slang term for a blind panel connector (also called a butt-joint fastener) often used in scenic construction to join together stage decks or scenery in a butt joint.
 These are two part connectors (male and female) that draw together and lock.
 The two most common types are the cam and acceptor and more traditional hook and pin version.
 These devices generally use an hex key to operate the locking mechanism via a small diameter hole either through the face or rear of the panel.
 When locked, the considerable mechanical advantage offered by the cam or hook holds the panels tightly together.
 Coffin locks can be installed directly into a mortise cut into each panel for total concealment except for the locking hole or mounted to the rear of the panels.
 Many small theatres use stock platforms with coffin locks built into the frames.
Hex is a strategy board game for two players played on a hexagonal grid, theoretically of any size and several possible shapes, but traditionally as an 11×11 rhombus.
 Players alternate placing markers or stones (Go stones make ideal playing pieces) on unoccupied spaces in an attempt to link their opposite sides of the board in an unbroken chain.
 One player must win; there are no draws.
 The game has deep strategy, sharp tactics and a profound mathematical underpinning related to the Brouwer fixed-point theorem.
 It was invented in the 1940s independently by two mathematicians, Piet Hein and John Nash.
 The game was first marketed as a board game in Denmark under the name Con-tac-tix, and Parker Brothers marketed a version of it in 1952 called Hex; they are no longer in production.
 Hex can also be played with paper and pencil on hexagonally ruled graph paper.
Catan: Cities & Knights (German: "Städte und Ritter" ), formerly "The Cities and Knights of Catan" is an expansion to the board game "The Settlers of Catan" for three to four players (five to six player play is also possible with the "Settlers" and "Cities & Knights" five to six player extensions; two-player play is possible with the "" expansion).
 It contains features taken from "The Settlers of Catan", with emphasis on city development and the use of knights, which are used as a method of attacking other players as well as helping opponents defend Catan against a common foe.
 "Cities & Knights" can also be combined with the "" expansion or with scenarios (again, five to six player play only possible with the applicable five to six player extension(s)).
A distelfink is a stylized goldfinch, probably based on the European variety It frequently appears in Pennsylvania Dutch folk art.
 It represents happiness and good fortune and the Pennsylvania German people, and is a common theme in hex signs and in fraktur.
 The word "distelfink" (literally 'thistle-finch') is the German name for the European goldfinch.
A set screw is a type of screw generally used to secure an object within or against another object, normally not using a nut (see bolts compared with screws).
 The most common examples are securing a pulley or gear to a shaft.
 Set screws are usually headless (also called "blind"), meaning that the screw is fully threaded and has no head projecting past the major diameter of the screw thread.
 If a set screw has a head, the thread will extend all the way to the head (whereas a bolt might have an unthreaded shank between the head and thread).
 A blind set screw (known in the UK as a grub screw, quite possibly from its figurative resemblance to a soil-dwelling grub) is almost always driven with an internal-wrenching drive, such as a hex socket (Allen), star (Torx), square socket (Robertson), or slot.
 The set screw passes through a threaded hole in the outer object and is tightened against the inner object to prevent it from moving relative to the outer object.
 It exerts compressional or clamping force through the bottom tip that projects through the hole.
Candamir: The First Settlers is a German board game.
 It is the first game of the "Catan Adventure" series of games, which share a common theme (but not mechanics) with the "Settlers of Catan" games.
 As such, it was created by Klaus Teuber, and distributed by Kosmos in German and Mayfair Games in English.
 The name "Candamir" comes from the "Settlers of Catan" novel by Rebecca Gablé, where Candamir is the name of the main character.
 The same character is prominently featured in this game.
Hexene is an alkene with a molecular formula CH.
 The prefix "hex" is derived from the fact that there are 6 carbon atoms in the molecule, while the "-ene" suffix denotes that there is an alkene present—two carbon atoms are connected via a double bond.
 There are several isomers of hexene, depending on the position and geometry of the double bond in the chain.
 One of the most common industrially useful isomers is 1-hexene, an alpha-olefin.
 Hexene is used as a comonomer in the production of polyethylene.
The Settlers of Catan, sometimes shortened to Catan or Settlers, is a multiplayer board game designed by Klaus Teuber and first published in 1995 in Germany by Franckh-Kosmos Verlag (Kosmos) as Die Siedler von Catan.
 Players assume the roles of settlers, each attempting to build and develop holdings while trading and acquiring resources.
 Players are awarded points as their settlements grow; the first to reach a set number of points, typically 10, is the winner.
 The game and its many expansions are also published by Mayfair Games, Filosofia, Capcom, 999 Games, Κάισσα, and Devir.
The Feed icon is for indicating that a web feed is available on a web page.
 It was originally invented for the use of RSS, but it is also common for Atom and other web feeds now.
 The icon is normally orange, with hex code #FA9B39.
 The original icon was created by Stephen Horlander, a designer at Mozilla.
The acorn nut is a type of fastener which gets its name from its shape.
 Acorn nut is its common name and it is also called a crown hex nut, blind nut, cap nut or domed cap nut.
 It is a nut that has a domed top to cover the threads.
 This is to prevent contact with the external thread to protect the threads or protect other things the threads would rub against.
 In addition the dome gives a more finished appearance.
 It is usually made of brass, steel, stainless steel (low carbon content) or nylon.
 It can also be chrome plated and given a mirror finish.

Question: what does Hex and Catan have in common?
Answer: board game