Fantastic game!
Theme:
The use of less sanity being more power was a great take on the theme. I would really have loved to see some sanity effects in the game when you had less, like eternal darkness, that way there was a risk/reward for having less sanity. Plus most monsters could be cheesed by just staying far away and shooting. Rendering the losing sanity for more power, useless. Still a great use of the theme though!
Visuals:
The visuals were fantastic! This actually reminded me of the very first game jam I did with my teams game "out of Sight". Honestly such a cohesive style throughout the entire game (except for the purple bullets) lol
Sounds/Music:
You had great creepy and atmospheric music with decent sound fx in place. So it went very well with the overall design of the game!
Overall:
The game was a great 5-10 minute experience with appealing visuals and an intriguing atmosphere. I honestly wanted more from the game, such as a fuller story and more interesting level design. Also the utilization of the sanity meter could really help make the game pop even more! I enjoyed my play through of it!
I streamed it here, starts at minute 14: