Alien Invasyndrome is a 2D animated adult game by Mozu Field/Sixie, built on the Others engine and mixing sandbox, RPG, and puzzle play. It takes place aboard the deep-space exploration vessel Atlas, where an all-female crew searches for a way to continue humanity’s bloodline. You play as a hidden alien larva from a distant planet. It begins weak, so stealth, sabotage, and gradual growth are needed before you can dominate the ship. The adult themes include mind control, monster, and male domination.
The current build is Demo v2.0, released September 5, 2026 for Windows in English and Japanese, uncensored. Development is ongoing, and the creator warns bugs may occur. The demo concludes once the Lower Level elevator is entered. Destruction Points and Intrigue Points both start at zero, with no bonus. Destructible objects across areas grant Destruction Points. Intrigue Points come from guaranteed drops after brainwashing a character and releasing them. Save and load are said to be more stable.
Developer's description
Through the deep space of thousands of stars,
Exploration Vessel <Atlas> advances steadily.
With a carefully chosen crew of female, they seek for a way to continue the bloodline of humanity.
However, little do they know...
hidden in the silent shadow of the cosmos, another kind also strives to pass on.
Such kind hides in the crowd on the ship, an <Alien Larva> from a distant planet.
< This game is under active development, expect
bugs
happening and feel free to report. >
Spoiler
Tied to the fate of its bloodline,
it uses every way possible to grasp the faint hope.
Rooting on this vessel, turning these females into breeding beds.
To survive, this is its only way.
It's only another typical day on < Atlas >, another "normal" day.
In this game, you play as the Alien. Weak in the beginning, you should utilize your
stealth ability to sabotage and grow, eventually dominating the ship.
Demo v2.0
In V2.00, the game ends when you enter the elevator in the Lower Level.
For the Destruction Points and Intrigue Points used to obtain skills, there is no bonus this time, so both start from 0.
Destructible objects have been placed throughout each area, and you can obtain Destruction Points by destroying them.
Intrigue Points can be obtained by picking up items that are guaranteed to drop when you brainwash a character and then release them.
I believe Save/Load is now more stable than before, so please try that as well.
v0.99 Demo
・Added an event to move from the current area to the next area after boss battles.
・The kitchen area had numerous bugs that became difficult to fix, so it was completely removed and rebuilt.
・Implemented a pause button, allowing you to change language, adjust BGM volume, quit the game, or return to the title screen during gameplay.
※Save data loading is still unimplemented, so you cannot resume from where you left off after pausing.
・You can now attack enemies caught in traps.
・For this version only, the Trap skill is set to MAX from the start. Once bugs are nearly eliminated in this version, the demo will be complete. Future plans include implementing lower-level areas and creating the official title screen. After the demo is complete, we will prepare to announce it on the planned game sales site. Thank you for your continued support.
v0.97 Demo
・Charge Attack is now unavailable when the game starts
・Added event for acquiring the Charge Attack (By accessing the nest)
・Added Skill Tree menu for learning skills
※You may see a bug that says you can learn it again after the first time, ignore it cause it is WIP.
・Added event after boss fight (with sex animation)
・Now you may release hypnotized NPCs. Open the command list (C key) to select that function while you have someone hypnotized.
・The command list is now moved from B key (X on keyboard) to C key (C on keyboard).
v0.96.1 Demo
・Added the Security room mission and Area 1 Boss fight
・Demo now ends after boss fight
・Updated how attacking works to make it smoother
・No new sex scene
v0.95 Demo
・After the Prologue the game will be auto saved at that moment. You may press < 1 > on the main menu to load the save.
・Now you may use < Space > button to zoom in and out during sex animations.
・Added X-ray function for 2 characters (Machinist A & B). This is currently experimental, feel free to give comments regarding this.
・No new sex scene
v0.94 Demo
・Added Security Corridor event.
・Added new main cast NPC, the Machinist. (No scene yet)
・1 sex scene in the new event.
v0.93 Demo
Bugfixes
v0.92 Demo
・Kitchen is now functional
・Added 2 new mobs (Cooks),1 animation each
v0.9 Demo
・Added the full Doctor meeting event. (Mission system not implemented yet)
・Now getting hit looks more responsive
・Something might happen if you attack the Doctor...?
・Now you can repeat sex animation, the'd be some changes on the animation
・Upated UI
v0.83 Demo
・Bugfix
v0.82 Demo
・Added manual pose selection before sex scenes.
・Added sex animation stage control.
・Sex animations are now repeatable.
・Various bugfix.
v0.81 Demo
・Added Clinic, Laboratory and Cafeteria.
・Added 2 new mob crewmates.
・Added event of first meeting with Doctor.
(Dialogue event isn't implemented yet. This demo will end after the current event)
・Added Int and Str bars. Upgrading and upgrade resources aren't implemented yet.
・Charging while going into stealth mode is quite buggy.
When you get out of stealth mode while charging, the action will be carried out right after coming out.
・You may now skip the first entrance event by pressing Confirm.
・You may move diagonally now.
・Various bugfix.
v0.72 Demo
・Added Storage room, Clinic Corridor and Cafeteria Corridor
・Added Security Camera, Security Soldiers
・You may now hide under desks.
・Flamethrower will also burn objects.
・Security Soldiers' sex animation .
・Fixed attack.
v0.65 Demo
・Bug (digital) fix patch
v0.6 Demo
・Implemented Charge Attacks
・Changed the behavior of the security drone, now the drone can be destroyed when exhausting.
・Added HP gauge; when HP reaches 0, the game is over. In the future, the player will be revived in the base after it's built.
・The UI of the title screen was slightly changed for better understanding.
Charge attacks can be used to capture enemies from any direction as long as the alien is not seen. Charge attacks will be a skill acquired after leveling up in the future.
v0.4 Demo
・Alien attack effects are displayed.
・Fixed a bug that prevented attacks from hitting.
・Fixed a bug related to area movement.
v0.0 Demo
First release
Player reviews
Player rating5.0 / 5 · 20 ratings
Written reviews20 · avg 4.2★
Positive (4–5★)75%
Latest review2025-12-26
What players say
Most reviewers praise the premise and pixel art, but bugs and limited demo content lower some ratings.
5★14
4★1
3★2
2★1
1★2
Players like
Pixel art and animations are praised
Playing as sneaking alien has appealing concept
Promising demo with room to grow
Simple controls and stealth gameplay are easy to grasp
Common complaints
Frequent bugs and softlocks block progress
Current demo is very short and limited
Detection causes unfair waiting and low challenge
Best for players who enjoy stealth alien capture games with pixel art and adult themes.
Summarised from 20 written player reviews.
Mamadoulevoyou2025-12-26★★★★★
looks very promissing, and will likely be a great came, but my experience was pretty bad, i got softlocked 4 times and since it seems i can't save/load i had to re-do everything again (obviously the 4th times i stopped…
ingvary2025-10-05★★★★★
Very promising game. The premise - alien sexually assaulting humans on a starship - is simple but graphics are well done and the topic of evolving and getting stronger is very appealing. My only concern is that the game is…
Bad Game2025-09-26★★★★★
Love the game, the premise, everything. Its still a demo but its already great. Just needs more animations per woman, ship expansion for more areas, and it would be nice to have more mechanics with objects. I would like to…