I'm not a big fan of horror games. Given the choice to be scared or not, i'd rather not.

This line of questioning reminds me a Extra Credits episode so I wanted to share that. The episode talks about using uncanniness to instill fear. Note that the playlist contains all the shows they did that touch to horror (broadly construed).

I'm not sure darkness is necessary to a good horror setting but it does help a lot in creating creating horror. First it blurs the line between the uncanny and the unbelievable, I believe you'll register first what is familiar and then what is out of place, the uncanniness, but you won't be able to see how ridiculous or over the top what you are looking at is. Second if you create a setting where the player never have a direct encounter they'll fill the void with their own fears, which is more powerful and more universal than anything anyone could design since each player brings in the game what frighten them the more. To do that you need to give a place for the player to put their fears and a dark environment is a good way to give it to them.

An illustration of that limited perception as a vector for horror is how the experience of Silent Hill 2 was transformed when in the remake removed the fog.