In tabletop games and video games, game mechanics are the rules or ludemes that govern and guide the player's actions, as well as the game's response to them. A rule is an instruction on how to play, a ludeme is an element of play like the L-shaped move of the knight in chess. A game's mechanics thus effectively specify how the game will work for the people who play it.
A chess clock can be used to measure and limit the time taken by each player in a turn-based game.
The hexagonal board of Divine Right
Square tiles that join to form cities and roads, in the game Carcassonne
Game balance is a branch of game design with the intention of improving gameplay and user experience by balancing difficulty and fairness. Game balance consists of adjusting rewards, challenges, and/or elements of a game to create the intended player experience.
Dice add an element of chance to a game.
A game being moderated by a human gamemaster (right)