I know you say in the preface before the game starts that this will be pretty linear without to much exploration but if you want to make this a better game then at least you should set up some of the more key scenes to allow for interaction such as how evil or nice you want the character to go. For example if you want to help ashley or not, listening to the strange voice or ignoring it, and other various moments. Doesn't have to be anything too complicated just something to make it a little more interactive and to give more variety to the flow of things. A lot of visual novels have a pretty linear location path but allow for more in depth character interaction. This is less a game and more a story.
With that being said it's pretty good but considering the premise of the story, kind of wish the mc was a little less of a wuss.