A serious game is one where the objective of entertainment is secondary to the objective of addressing a serious issue.
Many serious games follow the Triadic Game Design structure:

• Reality (What is the topic you wish to address?)
• Meaning (What impact do you hope to have?)
• Play (How should the player interact with the topic?)

A World Health Organisation document with data from 2015 suggests that 322 million people worldwide are suffering from Major Depressive Disorder (commonly known as depression).
https://apps.who.int/iris/bitstream/handle/10665/254610/WHO-MSD-MER-2017.2-eng.pdf

Unfortunately, many of us do not know what we can do or say to comfort people that are struggling with depression. Some of us might feel urged to figure out the problem and guide them, but this can actually have a negative effect as vulnerable people can feel pressured when someone spends effort on trying to help them.
https://www.mind.org.uk/information-support/types-of-mental-health-problems/depression/for-friends-and-family/

This is an early prototype for a game that - I hope - will give people confidence, inspiration, and/or guidance when speaking to people struggling with depression.
Mental health struggles are not easily resolved, and finding the 'right' thing to say is incredibly complex. I do not claim to have the answers, but I would like to find and share ideas that help.

The prototype includes an introduction, and a big choice. The introduction is set on the first day of a new school, where you meet Koda. You share your interests with each other and become friends. 5 years after you meet, you find Koda burned out and acting distant. You have a choice of 3 common responses to the above scenario, and Koda will react differently depending on what is picked.

If the project is to continue further, I will need to work with mental health professionals (as misrepresentation of depression would not only defeat the goal of the project, but also insult those who have suffered), writers (in order to craft an interesting world and a cast of realistic, lovable characters), and artists (to help draw people in to the story).