It's a great game but I think that for a game that's only text, it doesn't deserve to be 4 euros. In my opinion, 1 or 2 euros is enough, as there's not much game play.
I've heard cost complaints from others, although usually it's just that it should be free, which isn't exactly a viable comment so long as things like food, mortgages or health insurance are not also free. It's on the lower end for prices by my publisher, which typically range from $2.99 up to $7.99 or $8.99 for some of the longest entries or those that are part of a very popular series. Based on the amount of time to finish a playthrough and the replay value (since you'll usually see, on average, less than a quarter of the total word count in a single runthrough in this one), it was the price they went with (I have the ability to suggest a price but it's still up to Hosted Games what they release it at). I should point out that it was a dollar cheaper at launch, and might have another sale at a later point as well. Almost any CoG or HG title should be purchased at launch if you want a deal, since they always come out at a reduced rate that is as low as it will likely ever be in its lifetime.
I think the issue comes in that interactive fiction straddles the line between a game and a story, so it has to deal with the fact that video games are extremely cheap or free on mobile, but e-published stories are often quite pricey if they're coming from a publisher as opposed to self-published.
Either way, I appreciate you at least taking a look at it!