Technology in Stellaris is divided into 3 research areas with each area corresponding with one of the research resources: Engineering, Physics and Society. Additionally, each of the ~300 techs belongs to one of 12 subcategories divided between the areas (most appearing pre-dominantly in one area though not exclusively).
The user interaction aspect utilizes a card shuffle approach rather than a traditional tech tree presentation, thereby introducing an element of semi-randomness into the system.
Research areas & fields[edit | edit source]
There are three different main research areas in-game, with each area corresponding with one of the research resources. Additionally, each research area has multiple subcategories, for a total of 12 such subcategories, and every tech belongs to one of these subcategories.
The areas and their subcategories are as follows:
- Biology: Food production, leader lifespan and policies, species modification, army types, some strategic resources.
- Military Theory: Fleet command limit, naval capacity, army buildings and statistics, claim cost.
- New Worlds: Tile blocker clearance, terraforming, starbase capacity, administrative capacity.
- Statecraft: Unity, edicts, leader pool and recruitment, planetary and empire capitals.
- Psionics: Exotic mid- to late- game technologies. Unlocked through the Psionic Theory technology.
The card system[edit | edit source]
Although the underlying technology system is based on the familiar tech tree structure, it does away with its standard interaction/presentation in favor of the card shuffle approach. This injects a semi-random element into research, making it somewhat less predictable as well as less linear.
Whenever the player is prompted to initiate a research project, the game gives them a "hand of cards" consisting of a semi-random selection of technologies available for research, which are picked randomly from a hidden "deck of cards" consisting of all valid research options that can appear.
Technologies are divided into 6 levels (T0 to T5) of advancement. Higher tier technologies require obtaining a certain number of technologies from the preceding tier in the same area of research (set at 6 for all tiers) before they become available as research alternatives.
Every time the player meets the requirements for a given technology to become obtainable, the technology in question is added into the main "card deck" and will then have a chance of appearing in the "card hand" whenever the game draws a new hand for the player to pick from. There is one basic parameter affecting a tech's chances of appearing in a given card hand:
- Weight – A base value denoting the relative chance (out of all the valid options) of a particular technology to be drawn as an alternative. This may be further modified by an empire's composition (ethics, civics, etc.) and its current state (scientist's traits, past tech, etc.).
To further increase variation, a tech which appeared as an alternative in the previous card hand will have its weight multiplied by 0.5 in the next draw.
As a rule of thumb, the more advanced a technology is, the lower its weight (and the higher its cost). Systematically important techs (e.g. terraforming) have a higher weight (typically between 150% and double normal) to help ensure empires get a chance to research them, whereas rare technologies have significantly lower weight (typically one-eighth normal without the matching expertise). Some factors increase the weight of rare techs:
- Being in a level 3 or higher Research Cooperative federation with another member who knows the tech doubles the weight.
- The Technological Ascendancy ascension perk increases the weight of rare technologies by 50%.
Example[edit | edit source]
Let's assume the game draws a card hand of 3 techs: Armored Torpedoes, Autocannons, and Exotic Gas Refining. Additionally, the lead engineering scientist has a Propulsion field expertise (matching Armored Torpedoes), and the previous card hand had Autocannons as an available option.
If these were the only three valid techs and only one tech were to be drawn, then each tech's chances of being drawn would be 29.1%, 12.5%, and 56.4% respectively (rounded to 1 decimal place). Realistically there are usually many more valid picks and so the probability of picking any given tech is significantly lower than the figures given here.
Research alternatives[edit | edit source]
Each card hand drawn will contain 3 research alternatives, which may be further increased by 1 for each of the following:
- Scientific Revolution unity ambition
- Self-Evolving Logic technology
- Science Division / Mindlink / Research Path Optimization discovery tradition
- Technocracy civic
- Natural Neural Network civic
- Static Research Analysis civic
- Research Cooperative level 2
Additionally, some research cards may be gained as permanent alternatives. They appear below the regular alternatives and are distinguished from them by a golden border surrounding the tech card's bezel. These alternatives are usually acquired (along with some partial progress) through post-battle debris analysis, from special projects, or from event chains. These options will always appear as available options when drawing a new card hand and will remain as such until completed.
If need be, it is possible to change an on-going research project at any point – without losing research progress – and continue researching it at a later time. It is important to note, however, that the saved progress does not scale with changes to technology costs (for better or for worse). This tends to lead to the tech's completion percentage getting lower as the empire increases its empire size.
Unlike a permanent alternative, there is no guarantee that the technology in question will appear in the next card hand drawn.
Research output[edit | edit source]
Each research area employs the use of a different research resource.
The research production may then be modified by the following:
Additionally, each of the resources may also have the following modifiers affecting them (these apply only to a single resource rather than to all of them):
Stored research[edit | edit source]
Whenever research output is not actively used, it accumulates as stored research. Stored research also includes research resources gained from other avenues, such as debris analysis, anomalies, events, etc.
This allows for a more "relaxed" approach research by eliminating the possible loss of research points due to forgetting to pick a research project while, at the same time, also simulating accelerated periods of research (as opposed to sudden "jumps") caused by newfound knowledge sources. The current storage levels can be seen by hovering over the appropriate resources.
Stored research effectively doubles research speed, as it is spent at a rate matching current output, as long as there is enough stored research.
The empire will supplement its engineering research by an additional +24 research points for the first 41 months and by another +16 research points in the following month, after which the stored engineering research will be completely depleted.
Research speed[edit | edit source]
Research speed represents a given expertise in a particular research area or field leading to shortened research time of related technologies.
Research speed boosts the effective research production in the following manner:
The most immediate sources of research speed modifiers are the 3 lead scientists. As the applied bonus depends on a scientist's skill level and overall traits, it is recommended to assign newly recruited scientists to command a science ship. Scientists on exploration duty tend to gain experience faster and, if one is in luck, they may also gain a new trait beneficial to research while leveling up.
Note: A research area without a leading scientist receives a −25% penalty to research speed.
Research Speed is affected by the following permanent or renewable modifiers:
Technology cost[edit | edit source]
As a game progresses, research option choices will begin to include progressively more advanced and correspondingly more expensive technologies.
Research progress[edit | edit source]
In general, research time can be summarized as the following formula:
Research progress is one of the key elements affecting the time it takes to discover new technologies. It is formulated as follows:
While it is possible for the monthly research progress to remain constant during the course of researching a certain technology, it is more than likely to fluctuate – for better or for worse – due to consequences of various actions (such as exploration, empire development, expansion, etc.). This, in turn, may increase or decrease the total research time of a given tech.
Example[edit | edit source]
This setup generates the following monthly research progress:
Assuming no further changes impact the above setup, the total research time of the tech would be:
Note: Partial research can refer to debris analysis, previous research, event rewards, etc.
References[edit | edit source]
- See for details.