Each character has a set of 6 attributes, the physical attribytes are strength, agility, dexterity and the mental attributes are willpower, intelligence and perception. Each time a soldier goes up a level he gets an increase in of these attributes. By adding the attributes of a soldier you'll get his level, however this will not match the level displayed by the game. In the game all levels are displayed as 11 steps lower than they actually are. How good a soldier is at an attribute is represented by a value, each value has a name which is described in the table below.
| 0 | Awful |
| 1 | Poor |
| 2 | Average |
| 3 | Good |
| 4 | Very Good |
| 5 | Excellent |
| 6 | Heroic |
| 7 | Super Heroic |
| 8 | Ultra Heroic |
The last value is reserved for skills and isnt used for attrbutes.
There are 14 skills, actually there's 15 if you include melee, but melee is never used in the game. The skills describe how well a soldier is at a certain task. The skills are represented in the same way as attributes, so the above table is used here aswell. A soldiers skill is calculated from his attributes and his trainings, we'll get to the training later on. The formulas are very easy as you can see in this table:
| Strength | Agility | Dexterity | Willpower | Intelligence | Perception | |
| Marksmanship | 0.25 | 0.5 | 0.25 | |||
| Rifles | 0.5 | 0.5 | ||||
| Handguns | 0.25 | 0.75 | ||||
| Launchers | 0.75 | 0.25 | ||||
| Throwing | 0.5 | 0.5 | ||||
| Psi Power | 0.5 | 0.5 | ||||
| Hit Points | 0.5 | 0.25 | 0.25 | |||
| Speed | 0.25 | 0.5 | 0.25 | |||
| Dodging | 0.25 | 0.25 | 0.5 | |||
| Observation | 0.25 | 0.75 | ||||
| Stealth | 0.5 | 0.5 | ||||
| Aliens | 0.75 | 0.25 | ||||
| Medical | 0.25 | 0.75 | ||||
| Capcaity | 0.5 | 0.5 |
So for example, a soldier of very good(4) agility and heroic(6) willpower will have a rifles skill of: 4*0.5 + 6*0.5 = 5.0 = Excellent. If the soldier instead had excellent agility he would have had 5*0.5 + 6*0.5 = 5.5, now this number needs to be rounded to an integer value, the rounding method used in the game rounds 5.5 to 5, NOT 6. So the soldier would still have an Excellent rifles skill.
There are 7 trainings available in the game, every skill trains the soldier in 4 skills, however a soldier can only be trained once in every skill. This table describes what trainings train what skills.
| Marksmanship | Rifles | Handguns | Launchers | Throwing | Psi Power | Hit Points | Speed | Dodging | Observation | Stealth | Aliens | Mecical | Capacity | |
| Sniper | x | x | x | x | ||||||||||
| Soldier | x | x | x | x | ||||||||||
| Grenadier | x | x | x | x | ||||||||||
| Psionic | x | x | x | x | ||||||||||
| Scout | x | x | x | x | ||||||||||
| Medic | x | x | x | x | ||||||||||
| Scentist | x | x | x | x |
From this table it is easy to see that every training except scientist trains at least one skill that no other training also trains. It also makes you wonder what it is about a scientist that makes him good at throwing.
The skills also have certain predefined attribute limits that must be met before the soldier can have that training.
| Strength | Agility | Dexterity | Willpower | Intelligence | Perception | |
| Sniper | Average (2) | Average (2) | Good (3) | |||
| Soldier | Average (2) | Average (2) | Average (2) | |||
| Grenadier | Good (3) | Good (3) | ||||
| Psionic | Good (3) | Very Good (4) | ||||
| Scout | Good (3) | Very Good (4) | ||||
| Medic | Good (3) | Average (2) | ||||
| Scientist | Very Good (4) | Good (3) |
How the skills are calculated from the attributes is defined in: tactical/configs/game/listofskills.txt
The prerequisites and effects of trainings are defined in: tactical/configs/game/listoftrain.txt
If you dig into the savegames, you'll find many of these values and data describing what trainings have been trained and so on.