Video games are created from scripts. Writing these scripts can be challenging.
Every decision a player must make is diagrammed and flow charted. Every detail must be described. This requires methodical planning.
First you need to devise a concept. This defines who the protagonist is and what he or she wants. What does his world look like. What are the obstacles stopping him from getting what he wants.
Next decide what kind of game it is. First person shooter, role playing, a game. Is it a simple linear plot
where the protagonist must win each level and then go to the next? If it is more complex than that, you must write numerous branches of plots depending on what the protagonist does.
Now write an overview of the entire story. Include all the major plot branches and what happens in each. After you have the main story fleshed out, you can go back and fill in the details of the structure.
Each important character, major location, and significant object will need a physical description and a back story or history. You don’t need back stories for incidental characters or simple objects.
Now write the flow chart using boxes with text inside and arrows indicating every decision the main character makes. These are described as well as what happens when he makes any of the choices available.
Write the interactions the character has with non-player characters. This can be a separate flowchart showing how a non-player character acts, says or responds to actions or speech.
Make the style of your script consistent and easy to read. When writing the script be sure to write the dialogue, what the character sees, camera angles and the decisions. The programmer will need to have descriptions of the objects, spaces and characters of each scene. Include all audio elements such as sound effects, music and other audio.