Alien Syndrome
Alien Syndrome stands as a defining action title on the Sega Master System. With polished gameplay mechanics and memorable level design, this classic delivers an experience that has stood the test of time.
- Developer
- SEGA
- Released
- 1987
- Platform
- Master System
- Genre
- Action
- Players
- 2P
- Rating
- 4.7 / 5 (1.3K)
- Last updated
Alien Syndrome Controls — Master System Keyboard Keys
Default keyboard bindings for Alien Syndrome on our in-browser Master System emulator. Plug in a USB or Bluetooth gamepad to auto-detect mappings, or rebind any key from the emulator settings menu.
| Keyboard | Console button | Typical use |
|---|---|---|
| ↑ | D-Pad Up | Move up |
| ↓ | D-Pad Down | Move down |
| ← | D-Pad Left | Move left |
| → | D-Pad Right | Move right |
| X | 1 | Primary action (jump / confirm) |
| Z | 2 | Secondary action (attack / cancel) |
| Enter | Pause | Start / Pause |
Rebind any key from the EmulatorJS in-game settings menu (gear icon → Controls). A connected gamepad auto-maps to the same buttons.
Alien Syndrome Longplay & Gameplay Videos
Watch a full playthrough of Alien Syndrome on Master System before you dive in — recommended for getting a feel for the game's pacing, story beats, and difficulty curve.
Watch longplay on YouTube
"Alien Syndrome" Master System longplay 1987
Alien Syndrome Cheat Codes
7 community-curated cheats for Alien Syndrome. Tick any to activate them automatically when you click "Play with cheats" — or copy a code into your own emulator.
-
Unlimited Time
00C0-7B06 -
Need One Hostage To Open Exit
00C0-7501 -
Keep Flame Weapon
00C8-ED01 -
Invulnerability
00C5-5502B67-7FE-3B4 -
Infinite Lives
3A6-F5F-2A200C0-5409 -
Infinite Time
7E1-22E-3B7 -
Keep fire weapon
3A3-ADE-2A2
External references
Frequently Asked Questions
When was Alien Syndrome released?
Alien Syndrome was released in 1987 for the Master System.
Who developed Alien Syndrome?
Alien Syndrome was developed by SEGA, available to play in your browser on RetroGameSpace.
How many players does Alien Syndrome support?
Alien Syndrome supports up to 2 players, ideal for couch co-op or competitive sessions on the Master System.
What type of game is Alien Syndrome?
Alien Syndrome is a Action game for the Master System, playable instantly in your browser — no downloads, no installs.
How can I play Alien Syndrome for free?
Open this page and click "Play Now" — Alien Syndrome runs free in your browser via WebAssembly emulation. No account, no payment, no installer.
Do I need to download anything to play Alien Syndrome in the browser?
No. Alien Syndrome streams from a public archive into a browser-side Master System emulator. Nothing is installed on your computer.
Can I save my progress in Alien Syndrome?
Yes. Save states are stored in your browser (IndexedDB) per game, and you can also use any in-game save the original Master System cartridge supported.
Does Alien Syndrome work on mobile devices?
Yes — the Master System emulator runs on iOS Safari and Android Chrome. Touch controls overlay the game; landscape mode is recommended.
Is it legal to play Alien Syndrome this way?
RetroGameSpace is a transient caching reverse-proxy and does not host first-party copies of Alien Syndrome. Game files are fetched on demand from publicly-accessible archives. You are responsible for compliance with your local laws and the bring-your-own-ROM principle.
