Object Orientated Design.

Concepts & Principles:
Normally Object Orientated Design (OOD) would begin after completion of the creation and would be used to flesh out initial ideas. Assets are often re-used in Games Development, for instance Foliage is re-used often when making a scene; Duplicating Tree's and Bush Models. Also Player Models can be re-used like for making background characters in a crowd for instance. When it comes to maintenance, it's more to do with the upkeep than actual game. You have to make sure that everything is working fine and is all up to date. Before you hand it to Quality Assurance. This means that if you are for instance given a certain time frame to complete a piece of work or part of the project then you will have to be efficient to complete it within the time limit. When working in a big group or a pair for instance then communication is key. You will need to be speak to each other to discuss ideas and express opinions for already set ideas. Sharing details is also important because you will need to both be on the same wavelength and working towards the same goal. Make sure that the final product is a Quality Product and that is fully patched and there are no bugs.

Game Objects: 
Game Objects are what a sprite is assigned too when using 2D Game Software such as Game-Maker. Objects have all the physics in them, for instance: They can contain settings for when you press left or right on your keyboard, the sprite will move. Weapons are exactly the same; they are created as Sprites but essentially come to life as Objects. You can code weapons to shoot objects like bullets whilst making it a Object. Rooms are basically Levels and Scenery is created just like Weapons.

Object Properties:
Within the Object Creation you can edit all sorts of things, you can essentially edit the whole thing and this is where the main Object comes to life. You can change the colour of your sprite and also the size of it, for instance if you're making a boss as opposed to a common enemy; you will probably want to make the Boss larger. You can also edit the Health a object has, in this example I'm talking about the difference between a common enemy and a Final Boss, a Final Boss would usually have increased Health to make a harder challenge. The speed is another thing you can change, because the Boss is bigger and has more Health, it might be slightly slower compared to the common enemy. Think of a Goomba as apposed Bowser.

Actions & Events:
Mouse and Keyboard Events are the main way of moving, interacting and progressing in a game, for instance in most standard PC games of recent times; WASD moves the character, E will usually interact unless it's been bound otherwise. This will all need to be coded, in basic format you could make it happen on Game-Maker by Setting W to move the sprite forwards for instance and S for backwards, etc. You can also set a Object to a destroy another Object when they make a connection, think of Snake on the Mobile Phone, when one pixel of the snake touches a pixel of the wall it is destroyed, this is set in the Events section in Object Mode. Timers and Scoring can also be set here, in a different scenario, when a Bullet destroys a enemy, you will get points in the corner of the screen for instance and this can also be set in Events.

Inheritance:
Inherited Events essentially means that if one Object changes it's method of events, it can be inherited by other sprites. Certain behaviours can be altered too, such as a dice rolling a fair amount, it can also be set to only roll 6's or roll more often then normal. Overriding events take place when a certain code is activated making a Object change its behaviour.