(click the image for a larger version. Seriously, there's no way to read it otherwise!)
In this chart, higher numbers are better; e.g. 50 means it was #1 on the comics chart that Friday, 49 means it was #2, 48 means it was #3, etc.
Awareness was slow to build, with none of the issues charting until issue #3 was released. Interest gradually built (a classic word-of-mouth scenario). The game was released on April 16, and you can see the explosion of interest in the Fridays immediately before and after the release date. After that it settled into a predictable pattern: each week a new issue debuted—usually in the top five—and then hung around for another week or two.
Clearly Injustice: Gods Among Us was a digital success for DC, and one that they hope to replicate as the first issue of Injustice: Year Two was released last week. There's also a digital first tie-in comic to Scribblenauts Unmasked, but so far none of the issues of that have charted (there have been four so far).