There is little point in beating around the bush about it: the obvious comparison for Debug is Event Horizon. While the subplots and backgrounds may differ, both films deal with the same scenario: an evil that has taken over a spaceship and a crew that comes to investigate. Comparing the two, it is peculiar to find that the reason Event Horizon worked so much better has nothing to do with its production values and everything to do with its focus on atmosphere—an area where Debug has every opportunity to match it, and simply fails to do so.
To its credit, Debug manages to stand up fairly well in quite a few aspects and punches well above its budget in terms of production values.
The acting is all right, with the exception of Jason Momoa's campy creep performance as I Am. Perhaps, already having achieved fame as Khal Drogo in Game of Thrones, he did not feel the same need to distinguish himself as the other actors. Perhaps the role simply did not suit him. Either way, the lacklustre sleaze he brings to the role cheapens and stifles all tension and drama whenever he is on screen. Jeananne Goossen and Sidney Leeder, in contrast, bring life and character to their roles, whereas the rest of the cast is simply passable.
The visuals in Debug are not without flaws, but they are at times gorgeous. (The HUD effects, in particular, stand out.) Sadly, they sometimes fail to impart a feeling of reality—of substance. Future technology may be clean and durable, but any surface will have wear and tear. In Debug, they tend to look like freshly moulded plastic—featureless and flimsy. Strangely, this does not seem to be down to capability so much as aesthetics, as it is true for the set as much as the CGI. As a whole, though, the visuals work, and most of the time the set and the CGI fit well together.
Sound effects are generally fair to pretty damned good, although they tend to fail to produce a sense of presence. The same goes for the score, which seems to have been mixed as so to be unobtrusive rather than evocative—a strange choice for a horror film.
All in all, it would seem Debug has enough good points to provide a solid horror experience. (After all, many films have done so with less.) As sci-fi horror is a genre I love and the space-based variety is woefully underrepresented, it disheartens me to say that it does not—and for rather bizarre reasons. You see, while the production would have worked well for a sci-fi drama, its manner of presentation promotes detachment rather than immersion. The tension never grabs you and events never draw you in, making the actual horror elements fall flat. Part of it is editing, but choices made in seemingly every aspect of the film—from character exposition to camera angles—exacerbate the problem. The effect, tragically, is an audience indifference this type of narrative can ill afford, making a film that could have, should have been a rough gem turn out to be just another barren space rock.
Debug is, in the end, a mediocre film with several massive, bulky cargo holds full of wasted potential due to an almost mindless indifference to the core driver of every good horror film—atmosphere.