Most game-to-manga adaptions often use original game CGs in varying resolutions and nothing else. This one has quite a bit of original artwork drawn by the original illustrator. This is a pretty good product.
@Wifriback Nevermind, you're correct. Some of the art looked new to me, but it'll all from the original game CGs.
I love the game so it was curious reading this. They changed the plot quite a bit for this, and rearranged events a bunch. The main thing that kind of ruins it for this version is it heavily cuts down on the setup, making her seem way more easy than she is in the game, or like some events are very rushed, which was crucial to making it exciting. I think it would've been better to just show the Dojima route and give it more time instead of cramming all the routes into a short manga.