How to Play SETI: Probes, Scanning, Data & Alien Life

The turn in one minute

1. Look at your credits, energy, cards, publicity, probes and data. Choose one main action you can pay for.
2. Resolve the action and any free effects or missions whose conditions you meet, following their printed timing.
3. Pass when you are done for the round. The first player to pass rotates the Solar System and selects an end-of-round card as shown on the player aid.
4. Once everyone has passed, gain income and prepare the next round. After round five, score the end game.

The eight main actions

• Play a card: pay its cost and resolve its white effect. Some effects let you tuck a card from your hand for income; a card is used for only one of its benefits. Missions printed on played cards can be conditional or triggered.
• Launch a probe: place a probe at Earth, ready for later movement and missions.
• Orbit: send an eligible probe to orbit a reachable planet or moon and take the indicated reward.
• Land: use a probe to land at a reachable location, taking its indicated reward and potentially finding a life trace.
• Scan: mark signals in distant sectors according to your telescope technologies. Sector wins can produce points and life traces.
• Analyze data: when your computer is full, clear its data to gain the indicated life trace and other printed benefits.
• Research a technology: rotate the Solar System, take an eligible tech tile and gain its reward. The techs improve later actions; you cannot take two tiles from the same stack.
• Pass: finish your participation in the round, resolving the pass steps in order. You take no further turns that round.

How free actions fit around the main action

The player aid lists options such as discarding a card for its free-action corner, buying movement with energy, buying a card with publicity, and exchanging two matching resources for another type. Card effects may add their own free actions. Use these to fund a main action or finish a mission; a turn still has only one main action.

Probes, rotation and timing

Probe movement and the rotating discs make timing a resource. Before paying to move toward a planet, check where that destination will be after rotation. An orbiter, lander or sample can give an immediate reward and help a mission; compare that with scanning, which can win a sector and contribute to alien discovery. You can mix the routes rather than committing to only one.

What does data do?

Scanning and other effects place data in your computer. Filling it makes the Analyze Data main action available; analysis turns that collected data into a life trace and printed rewards. Plan the action cost as well as the data collection, since a full computer alone does not complete the analysis.

When do aliens appear?

Two alien boards begin face down. Life traces from scanning, landing and data analysis fill discovery spaces. When all three spaces beneath one board are marked, reveal that species after the triggering turn and follow its rule sheet and setup. Its own research spaces, cards and any special scoring can then enter play. You can learn the species when it appears without reading every alien rule before the game.

How the game ends

After the fifth round’s last pass, score cards with gold end-game boxes, the gold scoring tiles and any alien-specific end-game step. Most points are earned during play, so use the full scoring checklist before putting pieces away. Tied highest scores remain tied under the base rulebook.

Common first-game mistakes

• Taking several main actions in one turn; the player aid allows one.
• Confusing a life trace with discovering a species; all three spaces for a species must be filled.
• Forgetting that Analyze Data requires the full computer and its own main action.
• Assuming every gold scoring tile rewards the same thing; inspect the chosen sides and your markers.

Example: choosing an efficient SETI turn

Suppose you have a probe near a planet, some energy and two project cards. You can spend your main action moving toward an orbit or landing reward, or use a different main action to play a card, scan or research a technology. Free actions may help adjust the resources you need, but they do not ordinarily give you unlimited main actions.

Illustrative decision: if orbiting this round also helps complete a card mission, it may outperform a generic resource action. If you are one data space away from filling your computer, scanning could make your later Analyze Data turn more valuable. The better option depends on the rotating solar-system board and the objectives in play.

Orbit, land or scan?

Orbiting is a way to use a probe near a planet or moon and take the indicated benefit. Landing is a separate action with a different reward and possible life-trace opportunity. Scanning instead spends a main action on the telescope board, using the game’s scanning rules and your technologies to place signal markers.

All three can contribute to discovering alien life through different routes. Consider not only the immediate points but also whether the action advances an alien discovery, fills the computer or triggers a mission card’s condition. Consult the exact planet/moon icon and technology wording before paying costs.

Data analysis: why a full computer is not enough

Data accumulated in your computer is not automatically converted into a life trace. When the computer is full, Analyze Data is its own main action, and you must follow that action to clear the required data and receive the indicated reward.

Example: you scan and gain the last data you need. You have prepared the analysis, but you normally cannot also take Analyze Data as a second main action on the same turn. Another player can act before you next have an opportunity.

Planning this action economy is especially important near the end of the fifth round, when an unconverted opportunity may not produce any further benefit.

What happens when an alien species is discovered?

Life traces gradually fill the discovery spaces below the alien boards. When the specified three spaces beneath an alien board are completed, that species is revealed after the triggering turn and its species-specific rules enter play. A single trace is progress, not a full discovery.

Because the two possible alien species can change how later actions work, it is sensible to leave some tactical flexibility in your engine. Do not spend a long time memorising alien effects before playing: the publisher’s game is designed to reveal those systems during play.

Rules reference: Czech Games Edition base-game rulebook and player aid. These examples are strategic interpretations rather than quotations from the printed rulebook.

More SETI guides

• Game guide
• Strategy
• Scoring
• Space Agencies expansion

Publisher sources and scope

Checked September 2026 against the CGE rulebook, player aid and publisher game page. Card and alien text can add exceptions; this covers the base game.