Short cosmic horror solo TTRPG about exploring the void and trying not to succumb to the toll it takes on your psyche.
At four pages plus a character sheet, this is a little more complex than a one-page game but almost as easy to pick up. The mechanics make sense and the thematic depletion of your capacity to succeed the longer you explore (via decreasingly powerful dice) is very satisfying.
The main frustration of this game is also thematically appropriate - there are only the merest hints of what you might encounter in the void, so it's up to you to try to figure out what your character is experiencing. While there is value in leaning into the fear of the unknown, this runs the risk of falling flat if the player's imagination struggles to populate the void with sufficient horrors. An optional table of slightly more specific prompts could have helped reduce the chance of this issue.
It's always good to see built-in safety guidance and content warnings. It's fantastic that the 'Succumbing' mechanic is described as a representation of the mental impact of exploring a space not native to your reality, and that the player can make a 'Grounding' check to mitigate this - and recover their ability to do so by spending time closer to their own reality. It may seem like a small thing to those without mental health conditions, but this is such a refreshing approach compared to old-fashioned 'Sanity/Madness' tracks that just creep inexorably upwards in traditional cosmic horror games.
Overall, Cthonaut offers a good starting framework for an adventure in the void, but your mileage may vary depending on how inspired you are to flesh out the details. 3/5 stars - enjoyable.