A hex crawl is a type of roleplaying adventure in which the Game Master creates (or uses a commercially/freely available) map of a large-ish wilderness area, mapping out terrain broken up into a grid of hexagons. The hexagons usually represent areas a few miles/kilometres across, so that an adventuring party travelling across the landscape might traverse a handful of hexes in a day of travel.
If visibility is good, the travellers may get to see the terrain of the immediately surrounding hexagons before choosing which direction to go. They may follow landscape features such as rivers. They may try to maintain a compass direction. Or they may wander randomly or even get lost and turned around.
Specific locations on the map will contain predetermined encounter opportunities, such as a cave complex inhabited by goblins, or a dragon's lair, or a dungeon complex beneath a ruined tower. Some hexes may contain bastions of civilisation: villages, towns, or cities.
The heroes are free to go wherever they want. To explore freely. Or maybe to attempt to follow a treasure map they might possess, or to try to locate some semi-mythical place. It's a vast, wide world out there, and they can do anything they want!
The Alexandrian gaming blog has a fantastic essay on hex crawls (broken into several parts, so click through if you're interested).
Commentary by memnarch (who has not seen the movie)
What on earth is wrong with those troopers? Completely blank faceplates? Okay, that gives them a rather creepy feel which could be useful somewhere, but how do they see? There's nothing else humanoid in Star Wars that I recall that completely lacks eye hole features.
Weird troopers aside, I wonder how much damage the eleven or so fighters can actually do to this place. Maybe there's more spaceships on the way, but we don't have anything obvious to target here like a thermal exhaust port or flying inside to shoot the big reactor.
Idiots indeed. PIE fighters shouldn't be ready to launch facing inside the hexagon complex, they should be ready to launch facing outside. And if the minions are only told to launch, they shouldn't try turning around or guessing at the proper direction, they should ask where to go on their way out the door! And hopefully once they're out there, they'll start getting shot at and return fire without prompting.
Allan: All right, let’s light up that hexagon!
Snap Wexley: Destroying it might not do anything.
Allan: Nobody builds a single hexagon. We’ll crawl our way across this Moon destroying every hex if we have to!
GM: From the command room, Hux spots the fleet attacking.
General Hux: What happened to our shield?
Colonel Datoo: It was deactivated from an auxiliary control room.
General Hux: Send a squad to check it out! And launch PIE fighters!
Colonel Datoo: PIEs might be a bit cramped in a control room.
General Hux: I mean out there!
Colonel Datoo: Yes, general! You need to give clear orders in a military command chain!
General Hux: Or to idiots.