There are two different sorts of difficulty level - one that acts on a global level, and one acting on individual AIs:
Game Difficulty Level
As of v1.31:
Difficulty = (AI Level) (AI Intelligence)
- Cakewalk = 15 (Fool)
- Easy = 20 (Dunce)
- Simple = 30 (Beginner)
- Beginner = 40 (Sub-Normal)
- Normal = 50 (Normal)
- Challenging = 65 (Bright)
- Tough = 80 (Intelligent) *Full AI capability from here on*
- Painful = 85 (Gifted)
- Crippling = 95 (Genius)
- Masochistic = 100 (Incredible)
- Obscene = 120 (Godlike)
- Suicidal = 150 (Ultimate)
AI Intelligence Level
AI Intelligence level is per AI controlled race. When you select a game each race has a varying degree of intelligence based on the game difficulty selected above. Exact details are not known, but AIs on higher levels (masochistics and higher) get significantly more "points" to spend in race creation and are not bound to the same point-spending rules the human player is (e.g. they can have 80% bonus in military production); and bonuses to economy, production, research, influence, diplomacy, range, sensors range and miniaturization. These bonuses vary to some degree in each game. Please note it's hard to distinguish invisible bonuses from AI abilities until a player gets first spying level on the AI, so updated numbers (game version 1.5 and Dark Avatar 1.6) for Incredible, Obscene, and Suicidal are "educated guess".
In older versions prior to v1.31 it was known to be the following.
- Fool - The AI's economy is run at 10% of normal; no higher level algorithms are enabled
- Beginner - The AI's economy is run at 25% of normal; no higher level algorithms are enabled
- Sub-Normal - The AI's economy is run at 50% of normal; no higher level algorithms are enabled
- Normal - The AI's economy is run at 75% of normal; AI evaluates common human tactics
- Bright - The AI's economy is run at 100% of normal; AI evaluates most known human tactics
- Intelligent - The AI's economy is run at 100% of normal; from this level up to the highest AI expertly picks abilities and all known human tactics are searched and countered
- Gifted - The AI's economy is run at 105% of normal;
- Genius - The AI's economy is run at 125% of normal;
Updated for newer versions of the game (DL 1.5 and DA)
- Incredible - The AI's economy, production, and research are run at 200% of normal and it gets a ~20% bonus to miniaturization and +4 sensors,
- Godlike - The AI's economy, production, and research are run at 300% of normal and it gets a ~40% bonus to miniaturization and +4-5 sensors;
- Ultimate - The AI's economy, production, and research are run at 400% of normal and it gets a ~60% bonus to miniaturization and +5-6 sensors;
- And as Kblore mentioned, we really have no idea how the bonuses run these days. But those are the numbers from the debug.err file along with their associated game settings. Brad has yet to fill us in on the details of what exactly the AI does at each of these levels. In the past it has been economy bonuses past a certain point. This is suspected to still be true but the exact values are unknown.
- Exact levels for your current game can be viewed in the debug.err file in the installation directory.
- Warning! There's a big jump in game difficulty when going from Crippling to Masochistic. Most of players will need to severely change their playing style to be competent on Masochistic. Successful playing the game on even higher levels is impossible without expert knowledge of game mechanic and weak AI spots.