Stargate Worlds' combat is mostly ranged, is more action-oriented than the combat in other MMORPGs, and utilizes a cover system. Before today, that was all we knew. Cheyenne Mountain's Josh Kurtz (a familiar face, now) wrote up a developer journal describing Cheyenne's ambitions for cover-based combat. The journal is humorously presented in the form of an interrogation by a Jaffa. Stargate SG-1 geeks will smile.
Most objects in the world will act as cover, and players will be extremely vulnerable in open spaces like grassy fields or desert dunes. Kurtz described a scenario in which a player in Faction #1 might sit in an ambush position, waiting for a player in Faction #2 to wander into the open. If the player from Faction #2 is dumb enough to do that in a PvP area, he or she is likely to get ganked. On the other hand, he or she could move around in the woods nearby; it would take longer, but it would be stealthier and more secure.
Kurtz also said that humanoid NPCs will be the most common enemies, and since humanoids will build structures and trenches and stick near them, most combat will be in cover-rich areas