Land Collapse

Land Collapse is the fifteenth mission in Earth Defense Force 2025 and Earth Defense Force 4.1: The Shadow of New Despair. It introduces Tunnel Exits.

Objective
2025: The aliens are digging tunnels to move under the city. A tunnel entrance has been confirmed in the city. Alien monsters are emerging from it and soon the city will be overrun! We need to destroy the tunnel entrance and stop any more of those filthy creatures from emerging. You are to go to the location.

4.1: The aliens are digging tunnels to infiltrate the city's underbelly. At least one tunnel entrance has already been confirmed. Alien monsters have been emerging from it, and soon the city will be overrun! We need to destroy this tunnel entrance and stop any more of these filthy creatures from emerging. You are to head out immediately!

Storyline
The Tactics Officer starts things off this time by pointing out that giant insects are appearing in the urban areas, and that it seems they are building tunnels to them from their nest. HQ, sounding slightly more groggy than usual, asks if this means they were making "roads" safely underground.

Clearly sighing inwardly, the Tactics Officer reports that a large number of holes have been found in urban areas, placing some emphasis on these being tunnels as she repeats that they lead from the nest. HQ, now awake, springs into action, saying that if the holes stay open the bugs will "come and go as they please" and declaring that the EDF must destroy the Tunnel Exits. The Tactics Officer, deciding he's being too vague, orders Storm Team to destroy the nearest Tunnel Exit.

As it is destroyed, HQ decides there are still more of them and orders the EDF troops to search for them. He then grumbles a repetition of the same order after the new Exit actually appears, ordering the troops to "hurry, and destroy it."

Once it is destroyed, the Tactics Officer calls in that the giant insects have made another exit somewhere else. HQ, taking this personally, orders the troops to destroy it, growling "You giant insects, we won't let you above ground."

Since the giant insects inexplicably cannot hear him, the destruction of this Exit just leads to another appearing, which the Tactics Officer confirms. HQ, by this point very irate, snaps "destroy the tunnel exit!"

With the last Exit defeated, Aurora Situation Report pipes up, reporting on the Motherships deploying Quadruped Fortresses as heard in the previous level, adding that the EDF has constructed defensive lines to "prevent entry" of the Fortresses. The precise nature of these "lines" will be seen in the next level.

4.1 Changes
No changes, aside from the selection screen showing a picture of the first Tunnel Exit rather than a more useful but much harder to explain picture of the second.

Both versions:
4 x Tunnel Exit (3 x black Ants, deploys 19, 21, 26, 1 x Spiders, deploys 27).

Both versions
Land Collapse is designed to be a relatively gentle introduction to the concept of Tunnel Exits, though that is relative since this can be a very hard mission for a first-time player. It is recommended to bring a weapon for dealing with Ants and Spiders, and to ensure the other weapon chosen is capable of destroying buildings.

The Tunnel Exits appear sequentially with new ones appearing only when the previous one is destroyed; each has an accompanying group of civilians to keep it happy for a while before it tries to befriend Storm Team and a Ranger squad who cannot be recruited unless their commander dies. The Tunnel Exit itself may not seem to be taking damage at first since it is very tough and explosive weapons do not create the "spray of dirt" damage effect, but striking any part of the rocky surface will deal damage to it. Tunnel Exits do not stop spawning like the Anthills in Earth Defence Force: Insect Armageddon: if one appears to have done so, it is simply between spawn times. The Exit is only destroyed when a massive plume of dirt erupts from its center; it will then sink into the ground in defeat.

For a Ranger, the Stingray rocket launcher is ideal for hitting the Exits and the intervening buildings since its splash damage will hit the Exit along with anything coming out if it is aimed near the top; it is generally a good idea to save this for when the Exit is spawning enemies and use an assault rifle to damage the Exit the rest of the time. Volatile Napalm fired at the opening will also make any bug exiting the hole wish they hadn't.

A Fencer can make good use of his hammer-type CC Strikers to attack the hole and protect himself from the horde at the same time. Hand Gatlings or Dexter Automatic Shotguns are good for forging a path through the bugs so the Exit can be righteously spanked, though with dash-cancelling it is possible to completely bypass an Exit's guards and smack it around while they are still menacing their assigned civilians, though this is tricky with the final wave of Spiders. With the latter two holes this does require looping around to one side to avoid the spawned enemies, though.

A Wing Diver's LAZR, Idunn or Thunder Bow weapons deal enough direct damage to attack the exits themselves and are still good at engaging enemies, though some care must be taken not to run out of energy right when a new wave is coming out. Rapiers are even stronger against the Exits, but not as good in a straight-up fight outdoors; swooping in to destroy the Exit with one while its spawned enemies are preoccupied works, though another weapon will be needed to deal with them. A Plasma Launcher can also be useful here.

For an Air Raider, an E551 Gigantus can be useful here since it the splash damage from its main gun will allow it to attack both the Tunnel Exit and the bugs coming out of it at the same time. The Buster-type BM03 Vegaltas are very useful here too if the player has one, as is an EF31 Nereid if the player has mastered aiming the rockets. It is fairly hard to use support strikes in this mission since the two Tunnel Exits that are actually dangerous are heavily screened by buildings, though some creative use of Bombing Plans can drop shots on the Exits if the start marker is placed correctly. Whale's Artillery strikes can also be useful if the Air Raider can get them placed on the exit, since they will prevent bugs from exiting while they are in effect.

Of note online is that this mission is within the level limit for a BMX10 Proteus on Hard, a Proteus Burst on Hardest, and a Proteus Gamma on Inferno. While this will take some time to come out unless the players deliberately grind the early Tunnel Exits for supply credits, the level-appropriate Proteus will make very short work of the final wave of spiders. The locations are shown to the right: Exit #1 is straight along the road from the starting location, to the right behind a warehouse. Since it has little cover, it is fairly easy to deal with.

The same cannot be said of Exit #2, which appears among a cluster of buildings on the left side of the road and is the reason a weapon capable of destroying buildings is recommended. The trigger for this is Exit #1 being destroyed with #2 appearing a short time later, and so there may still be Ants from #1 hanging around when #2 appears. However, the Ants from #2, as ever, have to disentangle themselves from their surroundings before they can actually attack anything, which means they tend to come out in dribs and drabs rather than all at once.

Exit #3 then rears its ugly, um, rocks. This Exit only appears when #2 and all of its Ants have been put ot of commission. It is located a substantial distance away in the middle of the square next to the Space Needle-thing, on a raised platform, and a group of civilians spawns on the road leading to the square to keep its Ants fortified with vitamins and iron while Storm Team and the Rangers make their way over to it.

This Exit is quite difficult to deal with since the Ants tend to fan out into the surrounding buildings and ambush anyone heading up the road from multiple directions. Levelling these buildings helps, but this spawner generates more enemies than the previous two as well, so it is an uphill battle to get close enough to target it.

Once it and all of its minions are defeated, Exit #4 appears in a park area past the Space Needle to the left of the main road. This Exit bucks the trend of the others by spawning a group of Spiders, which immediately pounce on a group of civilians who spawned from their own secret civilian Tunnel Exit (presumably) between the new Exit and the square. Again. this is a tough fight without taking out the buildings, since Spiders are even more adept at ambush tactics than Ants and fighting them at such close quarters means their thread attacks deal a lot of damage.

Once the last Spider keels over, the mission is complete.

AFK farming
It is possible to "AFK farm" this mission for Armor pickups with a co-op team consisting of a Wing Diver and an Air Raider. This method is less efficient than the one using Valley Shadows and much less efficient than the one using the DLC mission Mountain of Change / Shifting Mountain (video here), and requires killing the leader of the EDF Ranger unit and is therefore Morally Bankrupt, but is detailed here anyway. It is best done on Easy difficulty since armor drops do not scale like weapon drops.

To do this, the first thing to do is to kill the EDF team leader with the Wing Diver, and neither kill or recruit his men. They will remain in position fighting the Ants from the first Tunnel Exit, but will not advance without a leader and therefore will not attack the second Tunnel Exit. The Wing Diver then moves to one of the rooftops near where the second Tunnel Exit will appear and aims a Thrust-type Rapier with a 0.5 second reload above where the opening will be. An elastic band is then applied to the trigger of this controller.

The Air Raider is then bought in to summon an EF24 Bazelart, destroy the first Exit, and land the helicopter right on top of the second, taking a small amount of damage from the Wing Diver along the way. Normally, AFK farming on a Tunnel Exit has the problem that the character on the Exit will be pushed off after a while and hence supervision is required (since there is a limit to how many item boxes can be spawned at the same time), but aircraft cannot be pushed around by collisions with normal enemies and so the Air Raider will remain in place picking up the crates as they are dropped.

As a note, this can also be avoided by firing a very overlevelled weapon straight up while standing on the Exit to shoot the insect corpses into the sky, which is how the Mountain of Change / Shifting Mountain method works, but this requires very high-level gear to produce the relevant physics effects.

A video of this having been successfully performed can be seen here. It should be noted that no more than 999 Armor items can be gained in a single mission.