I highly recommend AGAINST reading this manga for anyone that's interested in the series but hasn't played the game yet. It's just an adaptation made to be a cash grab without giving any respect to the original series.
You might say "It's only been 2 chapters, how can you be so sure?" well you don't need to beileve MY words but hear the creator's for yourself from the game's kickstarter page.
"I tried drawing a graphic novel, but while I was drafting the chapters, the story’s path seemed too linear. I wanted the audience to be able to explore outside of the pages, and the more I drafted, the more I felt that a graphic novel wouldn’t be the best medium to tell this story. I wanted the story to be fully interactive, and I wanted the audience to be able to make choices. All my ideas were coming to me in the form of gameplay. I needed to make OMORI a video game." - Omocat
on the game's kickstarter page.
On top of this, the story so far is completely unfaithful to the pacing and everything that made "Omori" into what it is.