I think that “more sinister than the actual game” is very common and usually absolutely okay, because the cover art has to attract the viewer.
It should just pique the viewer’s curiosity in a way that doesn’t lead to his/her disappointment when she/he plays the actual game subsequently. For this reason, exaggerations are a good stylistic element, because they are often funny and the viewer recognizes mostly that the respective cover is just a teaser.
Also, a cover doesn’t necessarily have to correspond to the game’s contents.
Example #1: The unknown pirates on the MI cover.
Example #2: Exaggerated poses (and muscles).
That couple above could have been Ray and Reyes as well.
Please note the chainsaw and the inscription “low on gas”! 