The theme of this jam is Lovecraftian Horror / Cosmic Horror.
Not so much tentacles and such, but the idea that humanity is insignificant in the long-term and our view of the universe is all wrong.
Elements of body horror (ie John Carpenter, Clive Barker, Junji Ito, Brian Yuzna, Stuart Gordon, etc) are welcome.
Slasher Horror (ala Friday the 13th etc) is not Lovecraftian Horror. Most of Junji Ito's stuff is a good example of modern cosmic horror.
Saya No Uta is a good example of a Visual Novel using this theme, as is our free kinetic novel, 'Arcane City: Lyn;Lin'.
You may use them for reference if you wish.
Get creative and have fun!
Arcane City Game Studios