From the introduction:
Depression Quest is a game that deals with living with depression in a very literal way. This game is not meant to be a fun or lighthearted experience. If you are currently suffering from the illness and are easily triggered, please be aware that this game uses stark depictions of people in very dark places.
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The goal of this game is twofold: firstly, we want to illustrate as clearly as possible what depression is like, so that it may be better understood by people without depression. Hopefully this can be something to spread awareness and fight against the social stigma and misunderstandings that depression sufferers face. Secondly, our hope is that in presenting as real a simulation of depression as possible, other sufferers will come to know that they aren't alone, and hopefully derive some measure of comfort from that.