Immersion is that part of games which involves the player becoming a part of the world which the game intends to represent. Generally this is thought of as a fictional, or narrative world, but it is not unheard of to become immersed in the world of an abstract game. Immersion is similar to the idea of the suspension of disbelief, a part of the experience of other narrative arts when the audience lets go of their awareness of the construct, and feels that they have entered the world presented.
In games, immersion is subtly different because the player is active in the world, as opposed to be a passive observer. Immersion is likewise somewhat more difficult to attain, as there are so many opportunities for the player's sense of involvement to be frustrated with the limits of the medium, especially in contrast with pure narrative forms. Few games (and we mostly think of computer games) can provide the player with the right kinds of freedom so that they do not constantly hit their heads on the game world, so to speak. If they feel that they are being constrained, especially due to technological limits, the immersion will break down, and their conciousness of the game's devices will come to the fore again.
It can be argued that narrative immersion is antithetical to games, insofar as narrative is antithetical to games. However contemporary games of many kinds employ narrative, and immersion is now considered a meaningful goal by many game designers. In any case, immersion is generally desirable. The player wants to enter the game as an environment, and come to a more intuitive understanding of its rules and patterns. Such an understanding is apart from believing in the reality of a narrative. It is about coming to know the game as a world unto itself, in the way an artist becomes immersed in the act of creation, unconscious of the tools which act as intermediary. This is as true in board games or card games as in computer games or role-based games. The ability to become immersed in the system of a game is a means of measuring the quality of its design.
Immersion can be increased by ContinuousWorld.