General Information[]
Stats affect your character in more general ways than Skills, but all of them are important to each class. Each skill is associated to a primary stat and raising that stat by 5 increases the corresponding skills by 1. So for example a Might of 55 would add 11 points to your Mechanical, Melee, Blade and Spear skills. 
Psi Power and its 7 related Skills do not follow this rule.
Stats are capped at 100, regardless of any bonus. When your stats are drained because of a temporary status effect however, your bonus will be deduced before your base stat is. So for example, if an irradiated Marine has 90 base Might and has +25 from an equiped Brawler PBA, he will still remain at 100 Might until the 15 Might "over the cap" has been drained. In that sense, having a "wasted" bonus can be useful.
The number of stat points a character receives at level up is dependent on Class :
- Marine and Ranger get 3 points
- Engineer, Psion, Warrior and Seeker get 2 points
- Scout, Striker and Shepherd get 1 point
Temporary stat bonuses or reductions (from Armor, Equipment or Status Effects) do not affect major perks, e.g. +10 or -10 Might from a certain armor will not affect inventory slots or maximum food capacity. However, they do modify skills and status effect resistance at all times. Serums Bio mods modify your base stats, while armor or weapon bio mods only count as temporary modifiers.
Also, all weapons have a basic Finesse, Might or Brains requirement. If you equip a weapon for which you do not meet the requirement, the game will warn you with a message and you will incur severe penalties when using that weapon. You can view a weapon's requirement(s) in its info screen.
Might[]
Might is a combination of the classic Strength and Constitution attributes. It governs your mastery of Melee combat, which is overall the most cost-efficient (and dangerous) combat style in the game. It only assists one utility skill, Mechanical, but boosts your maximum food capacity and inventory size quite a bit. Might is also used when resisting Disease and Poison.
- Each point of Might increases food capacity by 10 and base ability to shrug off the most common status ailments in The Pit such as Disease, Poison, and Stun.
- Every 10 points of Might will increase inventory size by 6.
- Every 5 points of Might will improve the skills Blade, Mechanical, Melee (including grenades), and Spears.
Finesse[]
Finesse is also an important combat stat, but behaves differently than Might. To understand all the benefits of finesse, it is important to understand all the benefits of theskills improved by it. Overall, it is a hybrid stat, supporting a solid mix of ranged combat skills and many strong utility skills as well.
- Each point of Finesse increases your resistance to a few vision-impairing status effects, such as Blind.
- Every 5 points of Finesse will improve many skills, including combat ones like Pistol, Knife or Rifle. On the utility side, Electronics and Traps have good synergy with Finesse. Lockpick opens most weapon containers.
- Since Finesse only really benefits you every increment of 5, it may be wiser to "bank" stat points to 5 if you plan on increasing this stat next. This way, if you find a powerful Melee weapon and run out of ammo in the meantime, you can always put those 5 points in Might instead. Or Brains, if you start stepping on nasty traps.
Brains[]
Brains is a support stat that helps you in many obvious and not-so-obvious ways. It governs your ability to detect traps and slightly improves your psionic potential. Similar to Finesse, it is important to know the effect of devices and related skills to grasp the full benefit of this stat. With the introduction of the Engineering skill and the return of Trap retrieval, Brains now has some consistent combat potential as well.
- Each point of Brains helps you detect Floor Traps before you step on them, and helps resist some mind-addling status effects such as Confusion.
- Every 5 points of Brains improves skills which you depend on to successfuly interact with most repaired or intact devices. Brain-related skills also offer alternative ways of gaining experience and dealing with dangerous situations. They are also vital in discovering new Recipes.
Each point of Brains also increases the amount of Psi Points at your disposal by 1 per point.
Psi Power[]
Psi Power is introduced with the Mindgames Expansion and governs your mastery over the game's new ability system, Psionics . This stat directly affects how often you can cast Psionics and how well you can defend yourself from psionic creatures. As certain Psionics are particularly expensive or have a short recharge, a larger Psi point pool becomes essential as you learn new abilities.
- Each point of Psi Power increases psi point capacity by 2. It also helps negate or diminish the effects of certain psionics like Fear, Paralyze or Drain Life.
- Power does not affect Psi skills (or the effectiveness of psionics).
- Psionic abilities, to a varying degree, are important to any character's success. A larger pool of Psi points also often means you are getting more out of full rests, since your cap is larger.