Game Writing and Design Guide Notes #2 - Story Theory and Dialogue
In games, we need to see the story, not hear someone tell it.
Dialogue in video games
Although most game stories are presented through dialogue, good dialogue comes from good characters, events, and conflicts. Dialogue is just the tip of the iceberg.

The most basic way to make dialogue interesting is branching, but do not make choices where both options are the same (for example, letting the player pick: OK or Got it). That will annoy players. Branches must have real differences.
Branches do not have to be menu options. They can also be changes based on the current state. For example, if the player blows open a door instead of using a key, you can have an NPC complain in later dialogue: “Damn, another door to replace.” That often adds immersion and surprise.
Sources of dialogue
Good relationships and dialogue can fully engage players. The best relationships between characters are mutual giving and taking, and the characters themselves should be full of doubts and opposition:

If you meet a guy in level 2 who betrays you, you will feel strongly about him in level 3. But what if he helps you in level 3? What is his goal? When you meet him again in level 4, what will you think? This is how the story becomes more interesting.
This shows that dialogue is driven by behavior choices based on characters’ internal motivations. Plot twists and the dialogue they create should always keep the game fresh.
Reduce shopkeeper text
Among the many kinds of dialogue, one is the most annoying: vendor text that repeats endlessly.

For example, when you talk to a shopkeeper, this dialogue often repeats. Try to remove or reduce it: trigger it once every five interactions, have the shopkeeper mention daily promotions, or switch to non-intrusive dialogue (such as overhead text instead of pop-up boxes).
Present tense
Game dialogue should reflect that “events are happening now.” When describing actions, make it feel like the action is unfolding in front of the player, for example:
Karl enters the room and releases the safety on his pistol.
Karl entered the room. He released the safety on his pistol.
For game scripts, the story always happens here and now.
Meta story
Stories in a game do not always need to be explicitly written. Meta stories are tightly connected to the world. They happen at the edges of the main plot, hinted at but never explained. They can be a few casual lines from a character, and players will fill in the blanks and create their own story.

Large background stories can be handled with very simple visuals. For players, building their own story in their head is also a key part of the game experience.