I'm loving the show don't get me wrong, but to play devil's advocate, does it have to be virtually a shot for shot remake of the game? Seems a bit pointless if so
Watching the series episode by episode alongside a "movie" of the gameplay cut scenes, I'm finding it fascinating viewing the creative decisions that change the concept from a game with a good story to a series with a good story.
The situation with Henry (no spoilers obviously) changes from simply another game task stage to be completed to one of character driven conflict to achieve a shared aim. And of course, Bill and Frank becomes a story in its own right, which is very much a departure from the game.
I'm reminded of the film "Let Me In". I've seen parts of the original Swedish version, but I hear the American version was virtually a shot-by-shot remake. Objectively, it could be seen as a testament to the high quality of writing in both that there' so little that needs to be done - it's simply a case of bringing the story to a wider audience.
I did creative writing at degree level, and it has to be said they've probably needed a lot of restraint to resist the urge to try and "make things better", or make wholesale changes whilst arguing they're keeping to the "spirit of the game".
I've not played Halo either, but I heard that was a bit of clusterfuck from many fans' perspective. It probably serves as a good warning not to mess around with the source material too much, but then Halo has a lot more lore attached to it also.