This is cover art by Paul Alexander for the novel Guardian by Thomas Monteleone.

I always liked this cover art. But whenever I saw it, I was reminded of the TTRPG Traveller. Not any other game, just Traveller.

I finally figured out why. The characters are carrying long arms, not pistols. Since basic Traveller does not have laser pistols, players who want to pack a punch are forced to carry rifles.

Other games have blaster pistols and other compact weapons.