What's the best way of promoting your game?
Define best. Usually it is money and letting others promote your game. Would you play games like Destiny or Skyrim if you had never heard of them? Would you search for them? How? They had massive advertisments. Skyrim at least had an existing fan base. But Destiny back than had a hundreds of millions advertisement budget.
There are more games than time to play. You need to look interesting at the right time at the right place.Ok, there might be people actually looking for horror visual novel and search. You only have 3000 other titles here matching that tags. Sogood luck, If I try 1 game every day, in maybe 5 years i try your game. Or not. There are new every day.
It is cute that you tagged singleplayer for a visual novel ;-) . only 600 other games have that with horror.