There are six difficulty levels in Alpha Centauri. From easiest to hardest, they are Citizen, Specialist, Talent, Librarian, Thinker and Transcend.
When you play a multiplayer game, each player picks a difficulty level, and a difficulty level is selected for the game’s AI. In that case, a player’s difficulty level might be different from the game’s difficulty level.
However, in a single-player game, your difficulty level and the game’s difficulty level are the same.
It is important to note that the effect of the difficulty level for computer players is inverse to the effect of your own difficulty level. While Citizen is the easiest level for you, it is the hardest level for computer players — costs are low and waiting periods are short for you, while costs are high and waiting periods are long for computer players.
In general, Librarian level is where the two meet — costs, waiting periods and other similar factors tend to be the same for human players and for computer players at that level. Difficulty levels are a major factor (but not the only factor) for each of the following game elements:
- Easier Diplomacy. At lower levels, computer players will be more likely to “go easy” on you in diplomacy, unless you have turned on the “Intense Rivalry” option, in which case they always use maximum ruthlessness.
- Delayed Gang Tackles. In particular, the tendency for computer players to “gang up on” the human player is controlled by difficulty level. Computer players will never gang up before Turn 100 - ((5 - DIFF) * 50), where DIFF is the player’s difficulty level (but with Intense Rivalry on, DIFF is always 5). Also computer players will not gang up until the player’s overall “dominance bar” is significantly higher than the dominance bar of the second-place player: it need only be 20% higher with Intense Rivalry, but otherwise it needs to be 50% higher at Librarian, Thinker and Transcend levels, twice as high at Talent level, and never happens at Citizen and Specialist levels.
- No Mind Control. At Citizen, Specialist and Talent levels, computer players will not use Mind Control against human-player bases.
- Secret Projects. At Talent and below, the other factions can’t start work on a Secret Project until you, the player, have its prerequisite tech, even if they already have the tech in question.
- Colony Pod. At Citizen and Specialist levels, building a colony pod at a size 1 base does not eliminate the base.
- No Early Research. At Citizen and Specialist levels, all research points accumulated during the first 5 turns are ignored (to avoid presenting a beginner with a tech decision right away).
- Command Center Maintenance. The Maintenance cost of the Command Center facility is equal to the best Reactor level you have available (1 through 4), but never more than half your DIFF, rounded up.
- At Citizen level, maintenance is always 0. At Specialist and Talent level, it is always 1. At Librarian and Thinker it starts at 1 and rises to 2 with discovery of Fusion Power. At Transcend level it starts at 1, goes to 2 with Fusion Power, and to 3 with Quantum Power.
- No Power Overloads. At Citizen and Specialist levels, Base Facilities do not experience power overloads when you run out of energy to pay maintenance.
- No Pop Lost to Attack. At Citizen level, your bases never lose population points when they are attacked.
- Random events do not occur before Turn [75 - (DIFF x 10)].
- No Prototype Cost. At Citizen and Specialist levels, you do not have to pay for prototypes.
- No Production Penalty. At Citizen and Specialist levels, there is no penalty for switching production “in midstream” at a base. Cost to Change Society. The cost to change social engineering is affected by your difficulty level (CHANGE = (the number of areas changed in a turn) + 1).
- CHANGE x CHANGE x CHANGE x DIFF = the upheaval cost