On the flip side you have Diegetic, which exist in a game world instead of being overlaid onto the game, very much being part of the games fiction. For example a player could press a button to make their character look at their watch to check the time.

Non-diegetic in terms of game UI, Non-Diegetic is what you would normally associate a typical game UI, an overlay on top of the game. They have the freedom to be completly removed from the games fiction. Non-Diegetic UIs can represent health and ammo or be a hotbar like in World of Warcraft. Non-Diegetic UIs are normally represented two dimensionally. 

Meta

Meta UIs are like Non-Diegtic UIs, the difference is that Meta UIs have some way of staying the fiction of the game. A great example is Call of Duty; There is no health bar, but when you are low on health the screen would be overlay with blood to show that you are damaged. Meta UIs are normally represented two dimensionally.

The term ICT is also used to refer to the convergence of audio-visual and telephone networks with computer networks through a single cabling or link system. There are large economic incentives (huge cost savings due to elimination of the telephone network) to merge the telephone network with the computer network system using a single unified system of cabling, signal distribution and management.

Extrinsic motivation, on the other hand, drives someone to perform a task simply for an external reward or to avoid punishment. Extrinsic motivation is what game designers take advantage of to design enjoyable games and we’ll see exactly how they do so through a variety of game mechanics.

Player Types 
Beyond simple motivation, game designers recognize that players come to a game with their own personality types seeking different kinds of enjoyment. It’s important to recognize this and creates experiences that allow each of the player types to thrive in the game. Player types are classically divided into four categories:

Achievers enjoy gaining points, levels, equipment and other concrete measurements of succeeding in a game. They will go to great lengths to achieve rewards that confer minimal gameplay benefit simply for the prestige of having it.

Explorers enjoy discovering areas, creating maps and learning about hidden places. They love to take their time to explore new areas and look around at their own pace.

Socializers enjoy interacting with other players, and on some occasions, computer-controlled characters with personality. The game is merely a tool they use to meet others in-game or outside of it.

Killers enjoy competition with other players and are there to win against their peers.

Game Mechanics 
By understanding the different player types within your game, a game designer can build experiences that create extrinsic motivation for each of these player types. Game designers have established a set of best practices for doing so, which manifest in individual game mechanics they choose to leverage to drive enjoyment and desired behavior out of their users.

Let’s take a look at ten popular game mechanics:

Achievement 
The achievement mechanic enables players to earn achievements, which are virtual or physical representations of having accomplished something. These are often viewed by players as rewards in and of themselves.

Games with badges, levels, rewards, and points are all examples of the achievement mechanic. We equally see such badges and levels used in apps like Foursquare, fitness apps, and more.

Envy 
The envy mechanic creates an experience where a player desires to have something that another player already has. In order for this to be effective, a player needs to be able to see what other players have (voyeurism).

Allowing players to showcase their badges, levels to other players, allowing players to visit each other’s farms in FarmVille, and leaderboards in general are all examples of experiences that create envy. The reality is all social products with profile and status updates inevitably create some level of envy with others through voyeurism.

Ownership 
The ownership mechanic allows players to control something or have it as their property, which they take pride in having.

Controlling parts of a game board or owning a vast army are game examples of this mechanic. Simply “owning” popularity by having a large digital representation of many friends is the equivalent of this on social products.

Progression 
The progression mechanic displays success granularly and is measured through the process of completing itemized tasks.

Leveling up your player from 1 to 60 is the classic example of the progression mechanic. Any kind of progress bar you create in an product or service is how this often manifests outside of games.

Status 
The status mechanic enables you to have a rank or level in a game that confers status in the eyes of the player and others.

Being able to brag to your friends about your white paladin level 20 in WOW is the status mechanic at play. Github conveys the status of developers on their developer profiles by visualizing and summarizing their contributions across various open-source projects.

Collection 
The collection mechanic enables players to create a collection of items, whether they are achievements, resources, or anything else in the game.

Collecting resources and badges are the classic game examples of this. The central action on Pinterest of pinning various visuals into your pin-board is also a great example of the collection mechanic at work.

Blissful Productivity
The blissful productivity mechanic takes advantage of the idea that playing a game can make you happier working hard, than you would be relaxing. Essentially, we’re optimized as human beings by working hard, and doing meaningful and rewarding work.

Grinding in WoW is the classic example of blissful productivity. Oftentimes when we are building app experiences we try to make things as easy as possible to avoid our users having to do work. But what’s equally important is enabling experiences that get them in a state of blissful productivity, encouraging them to do work in our apps quite willingly. It still amazes me the relatively small set of contributors that maintain all of Wikipedia, a great example of blissful productivity.

Appointment 
The appointment mechanic requires that to succeed, one must return at a predefined time to take some action. Appointment mechanics are often deeply related to interval based reward schedules.

Farmville requires you to come back to the game at a set time to water your plants or they will wither away. Happy Hours are a real-world example of the appointment mechanic at work.

Cascading Information
The cascading information mechanic releases information in the minimum possible snippets in order to allow players to gain the appropriate level of understanding at each point during a game narrative.

Games typically show basic actions first, unlocking more as you progress through levels. Well-designed app on-boarding experiences follow this same mechanic as opposed to putting all product education up-front.