The Flow-theory is a concept that states that activities that are in the balance between difficulty and skill are creating a state of flow.
Mihaly Csikszentmihalyi states that there are some activities that can put any human in an state of flow that is motivational. Lots of these are derived from activities like making music, climbing, dancing and so forth.
It is because these activities require the player to learn, set up goals and also because these activities are providing feedback and they make control possible.These activities also are enjoyable because they are making the player cease to act in terms of common sense, and start acting for the purpose of the activity. 
To understand better, the flow state is a balance between the skill level and the challenge of a task. The Flow state will never occur if the challenge will be insignificant in balance with the individual skill. State of flow which is motivational is more likely to occur when the activity has an above-average skill.
When a task is too difficult, it causes people to be anxious. When a task is too easy, it causes boredom. When the task is just right, we are in a state of heightened focus and immersion, or in other words a state of Flow.
How does it feel to be in the flow?
- Completely involved in what we are doing: focused, concentrated
- A sense of ecstasy: of being outside of everyday reality
- Great inner clarity: knowing what needs to be done, and how well we are doing
- Knowing that the activity is doable: that our skills are adequate to the task
- A sense of serenity: no worries about oneself, a feeling of growing beyond the boundaries of the ego
- Timelessness: thoroughly focused on the present, hours seem to pass by in minutes
- Intrinsic motivation: whatever produces flow becomes its own reward
How to measure flow?
- Nakamura & Csikszentmihalyi enlist the various ways of measuring flow, including pointers to two questionnaires: Concept of Flow
- Intrinsic Motivation Inventory (measuring intrinsic motivation): 10 Questionnaires
- John Marshall Reeve: Agentic Engagement Scale and/or Activity-Feeling States:Questionnaires
- Game Engagement Questionnaire
- Davin Pavlas Play Experience Questionnaire
In a game such as Angry Bird, playing it for the first time the player doesn't know anything about the game and how it works. The game offers at the first level only one type of bird (the red one) that the player has to slingshot at the pigs that are hiding behind wobbly structures. Once the player understands the rules of the game and shows a certain skill mastery, a second type of bird (the blue one) that has other features and thus makes the game more difficult. But because the players skills have already increased, the player is still kept in the flow-zone.
In this first person shooter, a player embodies the role of a human cyborg warrior who has been cryofrozen for some time and is now unfrozen for a mission of fighting an alien species. As the player doesn't know much about how the avatar works or moves, the introductory session is wrapped into a narrative where a soldier guides the player through the thawing process by testing vital features to see if everything works. Before the player is ready, the storyline demands the player to get into the action and successively encounters more and more difficult obstacles, enemies, and more sophisticated weaponry.
The traditional process for assigning authorizations to a user to access certain functionality and perform tasks in a business software is by having an administrator granting those rights. The disadvantage with that is that a) it requires a lot of resources on the IT side to grant those rights, and b) that the administrators don't really know whether the users have the skills to use those features.
By designing a level system based on the Flow-Theory, users can earn their way up to new authorizations and functions, without the involvement of administrators.
- Mihaly Csikszentmihalyi,Flow - The Psychology of Optimal Experience, Harper Perennial, 2008.
- Mario Herger,Gamification of Access Control, Enterprise Gamification.com, 2012.