Mycopunk Planetary Defense Guide: Holding the Railgun at Every Threat Level
The hold-and-charge loop, where to stand in the railgun window, and the build that survives Planetary Defense.
Planetary Defense asks you to power up a planetary railgun and fire it at a rival company's spy ship — while everything on the map tries to stop you.
It is the only rotating mission built around defending a fixed point, which makes it the worst mission for mobile builds and the best mission for players who want to learn Onslaught.
The loop
The mission has two states, and they alternate:
- Charge state. You power the railgun. Enemies spawn in waves and converge on the platform.
- Fire state. The railgun targets and fires. You are exposed and cannot move freely.
The skill is entirely in how you spend the charge windows: clear the platform perimeter before the fire window starts, not during it.
Build requirements
| Need | Why | Example |
|---|---|---|
| Area damage | Waves arrive in clumps toward one point | Gunship Cannon, Street Sweeper |
| A defensive layer | You cannot retreat during fire | Bruiser cubes, shields |
| Sustain | No resupply mid-hold | Repair Siphon |
| Short reload | Downtime is punished | Cycler over Trident |
This is one of the few missions where Bruiser is genuinely the best pick rather than a preference. The Modular Construction oddity turns the single shield into six solid cubes, which is exactly the tool for holding a small platform — see the Bruiser build.
Glider is the opposite: the wingsuit and Rocket Salvo reward constant movement, and there is nowhere to move. Skip it here.
Positioning
- Stand on the high side of the platform. Enemies path around the railgun body, which creates a blind arc; put yourself on the side they must cross.
- Never stand in the railgun's own firing line when it activates. The 2.0.3 fix stopped the targeting from eating movement input, so you can now walk out of the way — take advantage of it.
- Clear the ramp first. Every wave enters through the same access points; camping them is worth more than chasing stragglers.
Threat scaling
| Threat | What changes | Answer |
|---|---|---|
| Risky–Perilous | Manageable waves | Any coherent board |
| Treacherous | Armoured units in waves | Sunder |
| Deadly | Waves overlap charge windows | Area damage mandatory |
| Onslaught | Constant pressure, no clean windows | Pre-clear perimeter, defensive layer |
| Predicament | One mistake ends the hold | Two-player spacing |
At Onslaught the mission becomes a resource question: you cannot clear every wave, so you choose which spawn to leave and which to kill. Leaving the far ramp alone and holding the near two is the standard solution.
Co-op
Two players on opposite sides of the platform is the strongest setup:
- One holds the ramp, one holds the platform edge.
- Whoever is not charging covers the charger.
- Do not both charge at once — the exposure window doubles for no benefit.
With four players, two on each ramp and one dedicated to the railgun is more than enough; the fourth should be clearing the outer ring where armoured units spawn.
The 2.0.3 fix and what it changed
Before 2.0.3, the railgun's targeting mode swallowed movement input — especially on controller, where stick noise triggered it constantly. That made the fire window a death sentence on high threat.
Now the input passes through. The practical effect is that Planetary Defense is finally fair at Deadly and above, and it is worth revisiting if you skipped it. The same patch also improved mouse upgrade placement with a controller plugged in, so hybrid input is no longer a trap.
Rewards
Planetary Defense pays standard mission XP: 100 at threat 1 rising to 216 at threat 6. It is not a better farm than Saxonite Transport, but the mission teaches fixed-point defence, which is precisely what Ouroboros boss rooms demand.
FAQ
What do you do in Planetary Defense? Power up a railgun and fire it at a rival company's spy ship while surviving the waves.
What is the best build for Planetary Defense?
Bruiser with Modular Construction, plus an area weapon like the Gunship Cannon.
Why did the railgun feel broken before 2.0.3? Its targeting ate movement input. The 2.0.3 patch fixed it.
How much XP does it give? 100 at threat 1 up to 216 at threat 6, the same as most rotating missions.
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