ZE-GUN

For the similar weapon used by the Tactical Armor in Earth Defense Force: Insect Armageddon, see Turret (Ability).

The ZE-GUN and ZE Launcher series are deployable autonomous weapons first introduced for the Storm 1 character class in Earth Defense Force 2017. In Earth Defense Force 2025 and Earth Defense Force 4.1: The Shadow of New Despair, they are used exclusively by the Air Raider class, and the same applies to Earth Defense Force 2: Invaders From Planet Space where they are exclusive to that game's Air Raider. The same applies to the Air Raider in Earth Defense Force 5.

Description
The ZE-GUN and ZE Launcher are deployable sentry guns placed on the ground with the fire button and then activated with the alt-fire button. They do not have to be activated immediately, and will remain in place as long as the soldier using them does not reload them, allowing them to be set up as part of various dastardly plans.

Pressing the activate button switches on all currently placed weapons; the only way to hold off on activating one is not to place it at all. When they are activated they will automatically engage targets within a set radius with fire from whatever weapon is mounted on them; GUNs use machine gun fire, while Launchers fire unguided explosive rockets with splash damage. They have a finite amount of ammunition, usually enough to fire for 30-40 seconds, and once this is expended they will cease fire and disappear shortly afterwards. Each gun has its own allocation of ammunition, so there is no need to worry about dropping an empty gun because another has been firing too long.

The weapons do not have a hitbox and cannot be damaged in any way, and once active will fire until they run out of ammunition. This also means that guns cannot hit each other, so it is unnecessary to take such concerns into account when placing them.

Reloading a ZE-weapon will delete all weapons currently placed, even those that are active, and start a 20-second mysterious procedure that ends with more of them existing somehow.

They use the same method to select targets as lock-on weapons do; unfortunately, this does mean they tend to try to fire through walls a lot. Once they have started firing they do not tend to stop, and will often just shoot at wherever the last target was if no suitable target is within range. The rate at which the turrets traverse is based on their level; at high levels they will essentially snap from one target to another, while low-level guns take some time to rotate. In all games they have limited elevation, roughly 45 degrees off horizontal, and so cannot engage enemies flying at high altitude unless they are attached to something sideways.

Placement of them is important; if they are clustered together they will tend to waste ammunition and lose much of their crowd control ability since they will all be engaging the same target. Spacing them out is a better plan, and it is also a good idea to place them up high since their gunfire can harm NPCs, vehicles, and the character who set them, particularly with the explosive Launcher versions.

2017
The ZE-Gun in 2017 is a rig about the size of a car that Storm 1 can pull out of whatever pocket dimension he keeps his equipment in on a whim. It is thrown in an arc and seems to always land flat on the ground.

ZE Launcher
* Storm 1 clear bonus, Normal difficulty. Weapon does not drop in missions.

2017 Portable
Portable, seemingly due to hardware restrictions (since the ZE-weapons were rather noted for slowing down the original 2017), cuts the number of ZE-weapons right down, even turning the ZE-GUN 10 into the ZE-GUN 5. The guns are also individually weaker, many having less ammunition per gun as well as fewer guns.

ZE Launcher
* Storm 1 clear bonus, Normal difficulty. Weapon does not drop in missions.

Description
The ZE-GUN series return with a new model and slightly different handling to their 2017 incarnation. Rather than being thrown out in an arc, the toolbox-like undeployed guns are placed down onto the ground, slightly forward of the Air Raider's feet and dropped at the last second. If the Air Raider is standing at the edge of a platform or on an uneven surface the guns can end up attached to the side of it rather than the top, which actually provides some advantages since they can shoot straight up like this. They can also be dropped off the wing of an EF31 Nereid or HU04 Brute if the Air Raider is standing on it, which can actually work as a tactic against aggro'd Spiders since the altitude limit in most levels is too high for them to even attack the helicopter but they still move to its location on the ground.

ZE-weapons can also be placed on enemies, though this is not exactly easy; more productively, by looking down it is possible to place a gun on the ground when grabbed by an Ant or Dragon and then activate it to escape. Obviously, it is not a good idea to do this with a Launcher. If the Air Raider is grabbed by a Dragon which starts flying, facing the camera at the Dragon will plant the gun on it, and the gun will usually be able to hit the creature. Placing a ZE-weapon while grabbed produces an odd effect where the camera temporarily detaches from the Air Raider and follows the weapon placement animation instead.

ZE-weapons are buffed in 2025 with an extension to the search range of most models; it is no longer necessary to set them up within spitting distance of enemies, and the launchers are vastly more useful with the ZEX Laucher boasting quadruple its original range. There are downsides, though: the rate of fire of most guns is slightly lower, and for some reason there is now a 4.5 second pause between a ZE-weapon firing its last shot and the gun disappearing, which delays the automatic reload. Though less of an issue, rather than simply switching on like they did in 2017 they now have a short animation of the box deploying into a gun when they are activated, which means they need to be activated slightly ahead of time.

The weapons treat "forward" as the direction the Air Raider was facing when they were planted, and if moved on a vehicle the entire gun model will rotate to keep the same orientation. They can fire in any direction, but can only turn 180 degrees from this "forward" line in a particular direction, meaning they have a longer traverse time when switching between targets on either side to their rear; facing them towards their intended target maximises their targeting speed.

It is worth noting that the ZE-weapons' lack of a hitbox has a downside in these games, in that they are completely unaffected by Power Posts or Power Assist Guns. ZE-weapons can be placed on Vehicles to increase their protection from attacks by low-HP enemies, though this is a mixed blessing since they can also hit the vehicle itself if they are misplaced or enemies are coming from the wrong angle, including parts of the vehicle that do not have a collision box (cannot be stood on) but do have a hitbox (can be shot), like the main gun of an Epsilon Armored Railgun. As a result, very few vehicles are suitable for placing a ZE Launcher on since it can destroy them very quickly if it picks the wrong target.

More ridiculously, it is possible to climb onto the top of a helicopter and place ZE-GUNs on the rotors, since unlike tank guns these have a collision box, or ZE Launchers if the player has no deep desire for their helicopter to continue existing.

There are any number of complicated plans which can be carried out involving ZE-weapons, but they shine when they are deployed far forward of the Air Raider's intended fighting position while enemies are not aggro'd and then activated immediately after a strike on those enemies, with the Air Raider's position used to force the enemies to walk through the guns to get to him. Placing them on high terrain (such as the pedestal in the first image in this section) maximises their effectiveness since all ZE-weapons are based on line-of-sight projectiles, and they can be placed on objects a player might normally disregard such as the raised wall segments of destroyed buildings; as long as a placement point is wider than the undeployed gun box in at least one direction, they can be reliably placed there.

All but the tallest buildings in the game can generally be partially or completely scaled using normal jumps and their own features, allowing guns to be placed on balconies, stairwells and rooftops to protect allies from stray shots. For example, the upper balcony of the two-storey houses in the town and city outskirts maps can be scaled by jumping onto the hedge surrounding them, then onto the roof over the gate, then up onto the balcony.

Similarly, many vehicles that look too large to climb actually can be; a BM03 Vegalta can be scaled by jumping from the backs of its lower legs to its waist joint and them up onto its back, while a Depth Crawler can be climbed on by using the joints at the base of the legs as a first step.

One oddity of the ZE-GUNs and Launchers in 4.1 is that while reloading in an underground mission, the Air Raider's helmet light (which follows his weapon's point of aim) will be pointed down and to the right, making it very hard to see.

ZE-GUN
ZE-GUNs for the most part represent a linear progression where each model is simply better than the ones before it, with two exceptions:

The ZE Sniper is a low-level oddity that could be thought of as the first ZE Launcher given its behaviour, though it has no splash damage. It is slow-firing with extremely long range and deals high damage for its level, and is best used in open areas such as parks. Its search distance of 1,200 metres is almost the entire diagonal distance across a map, meaning most placements will be able to track any enemy in a level; care must be taken to avoid wasting the few shots the gun has trying to hit something the ZE Sniper has no line of sight to.

The other oddity is the ZE-GUN 10. This variant allows the placement of ten guns which individually have a small amount of ammunition, a low search distance (the same as the initial ZE-GUN and half that of other normal models) and a low fire rate, but higher damage than even the final ZEXR-GUN. While the ZE-GUN 10 has higher overall damage output per second than even the ZEXR-GUN if all ten guns are placed at once (2,800 DPS versus 2,100), it is quite hard to lay out ten guns so they use all their ammunition effectively. The ZE-GUN 10 can be effective if rather than placing all the guns at the same time it is used to drop single guns when the Air Raider is threatened by small groups of enemies, taking advantage of its infrequent reloads when used like this compared to other ZE-weapons.

In terms of their operational time for an individual activated gun, ZE-GUN 10s fire for about 30 seconds, the first ZE-GUN for about 34, and the rest of the series about 40 with the exception of the ZEXR-GUN, which lasts about 50.

ZE Launcher
These two weapons are a straight progression with the ZEX Launcher's only downside being its superior ability to blow up things the player does not want blown up. Both have an "up" time for an individual gun of about 40 seconds.

IfPS
The retuned Air Raider class in Invaders from Planet Space no longer has vehicles, and so his sentry gun has become one of his signature weapons, with a new level 0 version part of his starting equipment. ZE-GUNs are otherwise essentially exactly the same as in 2025 and 4.1, though for some reason they all have their damage halved.

Earth Defense Force 5
ZE-Guns are a basic part of the Air Raider's equipment as in IfPS, and now have the additional bonus that they reload even when they are not the currently selected weapon. Gun-based ZE weapons have been changed to no longer deal friendly fire damage to player-controlled characters or friendly NPCs: they will, however, still deal normal damage to unoccupied vehicles.

EDF 5's new upgrade system allows for improvements to a ZE-weapon's rate of fire, reload speed and number of guns that can be placed at a time, and to the blast radius of shots from a ZE Launcher. Stats below reflect maximum numbers: their initial figures are lower, with the default reload time being around 60 seconds.

ZE-GUN
Within this series, the ZER-GUNs boast improved tracking and a higher rate of fire, but a lower number of deployed guns at a time and lower per-shot firepower. The basic ZE-GUN is part of the Air Raider's starting equipment and starts with its placement stat maxed out.

ZE Launcher
As before, a slower-firing variant which fires explosive rockets with splash damage. The final variant is unlocked in the first DLC mission pack: as its level is over 100, it can only be earned by completing DLC 1 missions on Inferno difficulty. Its principle gimmick is that it fires much more rapidly than the other ZE Launchers, hence its lower per-shot stats and high capacity.

FZ-GUN
ZE-Gun mounting a short-range flamethrower instead of a gun. The first variant is only available as a DLC weapon unlock, and also has a unique ability in that it does not cause friendly fire damage, while all later variants do: as with ZE Launchers, this includes to the Air Raider himself. The DLC variant does not drop in missions and so cannot be upgraded, so its reload speed is fixed. Their large magazines give them an exceptionally long "up" time, allowing them to suppress areas for prolonged periods.

ZE Blaster
Exclusive to DLC 2, this variant is equipped with a powerful continuous-beam laser cannon which can penetrate multiple enemies: it is visually similar to the Raster Cannon weapon used by Cosmonauts. It has a fairly slow tracking rate. While it could be thought of as functionally an exceptionally powerful finale to the FZ-GUN series, it departs from them by lacking friendly fire damage like a normal ZE-GUN.

Trivia

 * The 2017-era ZE-GUN model is a Russian AGS-17 automatic grenade launcher mounted on a scaled-up version of its actual tripod.