The latest 100 Days at Sea update introduces an entirely new Alien Invasion event that unfolds as your survival progresses. Instead of unlocking everything at once, you’ll encounter several alien raids over different in-game days, with each raid revealing a new island, better rewards, and tougher challenges.
If you’re wondering how to unlock every Alien Island or claim the new Ray Gun, this guide walks through every stage of the update.
100 Days at Sea Alien Invasion Update Guide – Ray Gun, Armor
Unlike normal events, the Alien Invasion progresses naturally as you survive longer.
At certain in-game days, a UFO raid will begin, sending waves of aliens to attack your base.
After defeating every alien during a raid, they’ll drop a special Transponder.
Picking up this item reveals the next Alien Island on your map.
Each island has its own objective, and every completed island rewards exclusive gear or useful buildings.
First Alien Raid
The first invasion usually happens very early into a playthrough, around Day 6.
When the UFO appears:
- Defend your base.
- Eliminate every invading alien.
- Collect the dropped Transponder.
Doing so unlocks the First Alien Island.
First Alien Island Walkthrough
Once you arrive, you’ll immediately notice a giant hungry alien.
Instead of fighting it, your objective is to feed it.
Step 1: Collect Strange Food
Search around the island for Strange Food.
You’ll need to gather a total of 20 pieces.
Fortunately, every piece is found on the same island, so there’s no need to leave.
Step 2: Feed the Giant Alien
Return to the large alien and hand over all 20 food items.
After eating enough, the alien explodes, revealing a hidden treasure chest.
First Island Reward – Food Processor
Opening the chest rewards the Food Processor.
This is arguably one of the best quality-of-life items added in the update.
Why the Food Processor Is So Good
After building it back at your base:
- Survivors automatically operate it.
- It creates Alien Soup.
- Alien Soup completely restores your hunger.
- It provides an effectively unlimited food supply.
Once you unlock this machine, managing hunger becomes much easier during long survival runs.
Second Alien Raid
The next invasion occurs much later, around Day 59.
The process is similar:
- Defeat every alien.
- Collect the new Transponder.
- Travel to the newly unlocked island.
Second Alien Island Guide
This island works very differently from the first.
Instead of completing a collection quest, you’ll need to destroy several UFOs.
Don’t Waste Time Fighting Aliens
One important thing to know:
The aliens on this island continuously respawn.
Trying to eliminate every enemy is a waste of time.
Instead, focus entirely on the mission objective.
Destroy Every UFO
Around the island you’ll find pieces of Dynamite.
Carry the dynamite to each UFO and place it nearby.
Repeat this until every UFO has been destroyed.
Once the final UFO explodes, two reward chests will appear.
Second Island Rewards
The two chests contain exclusive alien armor.
Alien Leggings
The first chest rewards:
- Alien Leggings
Alien Chest Armor
The second chest contains:
- Alien Chest Armor
Together, these provide one of the strongest armor sets introduced in recent updates while also giving your character a unique futuristic appearance.
Third Alien Raid
The final invasion happens much later into the game, around Day 262.
These enemies are considerably stronger than previous waves, so make sure your base defenses and equipment are upgraded beforehand.
After clearing the raid, collect the final Transponder.
This unlocks the Third Alien Island.
Third Alien Island Guide
The final island contains the mysterious Alien Mothership.
Outside you’ll notice an alien farm before entering the ship itself.
Inside is the biggest reward of the entire update.
How to Get the Ray Gun
The Ray Gun can eventually be unlocked inside the mothership.
While players using the Alien Class gain access much earlier, free-to-play players can also obtain it by completing the island puzzle.
Mothership Laser Puzzle
The mothership contains a laser reflection puzzle.
You’ll need to rotate mirrors so the laser reaches its destination.
The puzzle spans three separate rooms.
Room One
Rotate the mirrors until the laser exits toward the next room.
Room Two
Continue redirecting the laser using the available mirrors.
The beam must remain connected before moving forward.
Room Three
Finish the final laser path by correctly positioning every mirror.
Once all three rooms are connected, the central chamber activates.
Claim the Ray Gun
After solving every laser puzzle:
- Return to the center of the mothership.
- Open the newly unlocked chest.
You’ll receive the Ray Gun.
If you’re playing in multiplayer, the chest drops multiple Ray Guns so every player can receive one.
Alien Invasion Rewards
Here’s everything you can earn throughout the event:
| Raid | Objective | Reward |
|---|---|---|
| First Alien Island | Feed the giant alien 20 Strange Food | Food Processor |
| Second Alien Island | Destroy every UFO with Dynamite | Alien Leggings & Alien Chest Armor |
| Third Alien Island | Solve the three-room laser puzzle | Ray Gun |
Final Tips for the Alien Invasion Event
Before jumping into the Alien Invasion update, keep these tips in mind:
- Always defeat every alien during raids so the Transponder drops.
- Don’t spend time fighting endlessly respawning aliens on the second island.
- Collect all 20 Strange Food before returning to the giant alien.
- Upgrade your weapons before the third raid since the enemies become much stronger.
- If you’re playing with friends, complete the mothership together so everyone can receive a Ray Gun.
Overall, the Alien Invasion update adds a fun sense of progression to 100 Days at Sea, rewarding players with useful buildings, powerful armor, and one of the strongest weapons currently available in the game. If you’re planning a long survival run, it’s definitely worth completing every alien raid as soon as it appears.