Alien Motion Tracker

It is an unofficial GM-controlled motion tracker prop app for in-person Alien RPG sessions. The GM places and moves hidden echoes from one phone; a player uses another phone as the tracker.

For GM mode, you need at least two phones: one for the GM controls and one for the player tracker. Since the app is lightweight and free for players, one player can install it even during the session. Solo mode works on one phone.

You need to accept the local network permission on first launch. It allows the GM app and player apps to communicate.

The app does not use the internet, but GM remote control requires Wi‑Fi, preferably a private or home network, with the GM phone and player phones connected to the same Wi‑Fi.

I never use the internet to send any data. I do not collect data, and I do not plan to. Not even for debug reports.

Yes. Players can join a GM session for free. Not every player needs to install it: the tracker is designed around one active operator who sweeps, reads the signal, and calls out what they see while everyone reacts. Players only need to purchase if they want all tracker themes in solo mode, or if they want to support the project.

Use it when movement, proximity, or uncertainty matters: corridors, vents, darkness, sealed rooms, false positives, incoming contacts, or any scene where the danger should be felt before it is explained. You can use it with theater of the mind, a rough sketch, a table map, or no map at all.

The GM can place echoes, draw paths to move them, delete them, recenter when the player changes position, and pre-select or switch the tracker theme on the player device. It is a playable prop, not a rules module. On the GM side, positioning uses indicators for the four official range bands: Adjacent, Short, Medium, and Long. Extreme range is not included because motion trackers do not detect that far in the lore or the rules.

Several player trackers: yes, if their characters are grouped together. The app uses one shared party position, so every tracker reads the same contacts.

Several GMs in the same room: this is a known limitation. The app is designed for single-table play. In conventions or clubs, each table needs a specific, isolated Wi‑Fi network to avoid player connection issues.

No laptop or emulator support is planned for the tracker because it uses phone motion sensors like the gyroscope and accelerometer. It may work on tablets, as they usually have the required sensors; the GM interface should work well, but the tracker interface may feel too large. You could use it alongside Roll20 or Foundry, but the app is designed for in-person sessions where players physically sweep and rotate their phones.

No, not if you stay on the same platform. If you change iPhone, restore the purchase with the same Apple Account. If you change Android phone, use the same Google Play account. Apple and Android are separate stores, so a purchase on one will not automatically unlock GM mode on the other.

No. It is an unofficial fan-made table tool, not affiliated with or endorsed by Free League or the Alien franchise owners.