This article is for the PC version of Stellaris only.
These events will only occur if you have an observation post orbiting a pre-FTL civilization.
An observation post might detect an asteroid on a collision course with the planet. If it's not destroyed before it impacts it will cause an extinction event and leave the planet barren. It is also possible that the researchers will decide to sacrifice themselves by crashing the orbital post into the asteroid to deflect it.
While passively observing a pre-industrial civilization it is possible for one of your scientists to go missing while collecting plant samples. The scientist can be found killed by an animal a few days ago, giving -10% society output for a year. If it is not you will eventually receive a report about one of the native kingdoms rallying behind a religious figure and using technology far beyond the native level. The civilization will instantly advance to the industrial age. Eventually you will receive a transmission from the scientist revealing that it has grown tired of passive observation and considers it his/her duty to guide them. Later the planet will advance to the machine age prematurely, giving you the option to either launch an operation to extract the scientist or just observe.
Extracting the scientist requires two transports in orbit. The operation is as direct to the natives as expected, with them seeing your forces as they forcefully extract the scientist. There are three possible outcomes as a result of the scientist's disappearance. Either it will spark a world war, regress the civilization to the renaissance or steam age or have the natives find the observation post and destroy it with surface-to-space missiles. If the natives destroyed the observation post you will receive a transmission from the planet in a few months, asking you to send their "holy savior" back. Whatever the choice, the event will end.
If the scientist is not extracted then within two years of passive observation it will direct the civilization to destroy the observation post. Starting tech enlightenment on your own term can avoid this and create a normal protectorate. There is a bug that the scientist appear and contact you after loading a save in which it already introduced itself.
While passively observing a post-industrial civilization is possible for a squadron of fighters to come across a scientist shuttle and disable it. A special project will be issued to reach the crash site before the natives do. Doing so will grant a moderate amount of society research. If the project is not done in time the natives will secure the crash site. If the native civilization reached atomic age or early space age before the event this can trigger a nuclear war that will either revert the planet to an early age, wipe out the natives and turn the planet into a tomb world or make the planet an uninhabitable toxic world. Otherwise you will be contacted by the natives and asked to share some of your technology in exchange for the scientists. You can either agree for a cost of influence or refuse, leading to their execution a few days later and gaining a -10% unity modifier for 5 years.
Possible only during passive observation, you might discover that your empire's smugglers had set up a secret outpost on the planet and start a project to raid it. Raiding it will grant you energy and minerals.
Aggressive observation is likely to drive pre-FTL species to abandon xenophilia or embrace xenophobia. Unwanted circles or patterns in the crop fields can also make the species spiritualist. These changes will affect their personality if they discover FTL.
While aggressively observing a machine, atomic or early space age civilization you might get a request from the observation post to use a science ship to abduct natives in order to experiment on them. If you accept the special project require a level 3 scientist and finishing it will add a substantial amount of society research.
While aggressively observing a civilization that has reached at least industrial age you might identify a scientist that's brilliant even by your science's standards and be given the option to abduct him or her to work for your empire. If the abduction is successful you will gain a maximum level scientist with the spark of genius trait.
As part of aggressive observation missions some native test subjects have implants installed in their brains. These can malfunction and bring side effects such as hysteria or suicide, starting a special project to remove them. Doing so will grant a moderate amount of society research from the implant data.
Anti-Alien Task Force
As long as the observation post has the aggressive observation mission on a world that reached at least industrial age, there is a chance the fragmented nations will create together a military organization tasked with combating the alien abductions. You will be notified early that they started intercepting the abduction flights as well. Eventually they will reverse-engineer technology from the downed shuttles to track the observation post and destroy it with a surface-to-space missile. There is a chance that the observation post will manage to identify their underground base and propose a surgical strike. Accepting will start a special project that requires an army in orbit although it is not always successful.
If enough time passes several of the most important states will decide to withdraw their funding and support for the project, leading to its termination.
During covert infiltrations you might get a notice that one of your male covert infiltrators had fallen in love with a native female and disappeared. This will add a -20% reduction to the mission progress. Two and a half years later you will receive a transmission from the former infiltrator stating his motives.
The rogue agent can interfere with your process with three events, each with a MTTH of 60 months, and each can happen only once. He can either hunt operatives, cause a media witch-hunt, or have local authorities perform a mass arrest.
The infiltrating empire gets a chance to find the rogue agent, with also a MTTH of 60 months. When found, you can start the special project to eliminate him, which involves bringing a military ship into orbit. Blasting the city block with local orbital bombardment eliminates the agent, with the cover story being a meteor strike (and does no other harm to the pre-FTL primitives.) As with the rogue's actions, he can only be spotted once.
While infiltrating an atomic or early space age civilization it is possible for a failed operation to capture a leader to lead to an imminent war. This will add a -20% reduction to the mission progress but a far greater concern is the brewing situation. You will be given a special project to use a science ship to calm the situation through propaganda. Averting the war will add +20% to the mission progress, negating the lost one. Not starting the project in time will lead to a war that will quickly turn nuclear and wipe out the civilization and turn the planet into a tomb world.
The Great Pyramid
While passively or aggressively observing a civilization that's between Bronze Age and renaissance age it is possible to be told that a crew came down on the planet and proclaimed the chief scientist as a god and made the natives build a pyramid in his honor and you are present with the following options.
- Recall the team and scrap the project, destroying the observation post and throwing the natives back to the previous age
- Erase all your traces if the native interference policy is not passive, destroying the pyramid and killing a native pop
- Call it a hilarious prank if the native interference policy is not passive, thrusting the natives into the next age
- Take a gamble if the native interference policy is passive and your empire is pacifist or fanatic pacifist
If any of the last two options is taken then two or three months later either a religious war will start over the nature of your "god", killing two native pops and costing you 50 influence, or they will discard everything as a myth and analyze your pyramid intellectually, granting you some influence and society research.
There is a very small chance that an atomic or early space age civilization will become engaged in a nuclear war. The chance is increased with aggressive observation or covert infiltrations and is independent from the aforementioned events. It can happen even if there is no observation post in orbit, but then you will not be notified of it. If a nuclear war breaks out without intervention the civilization will always wipe itself out. There is a 75% chance the world will be turned into a tomb world and a 25% chance it will become a toxic world.
Technological Enlightenment Events
The following events can take place while trying to enlighten primitives:
- Xenophobe species might add a -20% reduction to the mission progress due to their distrust
- Xenophile species might add a +20% bonus to the mission progress thanks to their eagerness
- Species with the quick learners, natural engineers, natural physicists, natural sociologists, intelligent traits might add a +20% bonus to the mission progress
- Species with the slow learners or repugnant traits might add a -20% reduction to the mission progress
- Opposing ethics might add a -20% reduction to the mission progress due to opposing views
- Working together with your empire might drive the pre-FTL species to abandon xenophobia or embrace xenophilia
- Finally, the pre-FTL species might take on one of your ethics during the enlightenment