Okay then. Lets have three basic stats then.
Physical
Mental
Movement
For simplistic aproach these values could be from a scale of 1 to 10, with 10 being the best.
Physical will be the basic physical power of the character and would determine use of weapons and damage scale. Also a good gauge for the critter's overall health.
Mental would determine the intelligence gauge of the AI as well as determine the sensory capabilities and how well they are awareof their environment.
Movement would just determine how fast the character involved is.
Skills involved should be simple as well, also ranging 1 through 10.
Melee (Physical): How well one uses melee weapons.
Range (Physical): How well one uses range weapons.
Track (Mental): How well one will be able to track its prey.
Senses (Mental): Measures how well one can see and listen things around him.
Sneak (Movement): How well one can sneakily move around.
Basically add the skill rank level to the stat level and that is the overall bonus of the character to do that act. Now you can have a static system which has no random factors and just have it be raw skill and stat, like Bloodlines, or add in a random value of an additional d10 then add in stat and skill.
Armor can give a damage reduction, stronger the armor the less damage the critter takes. Also stronger the weapon the more damage you do. Also range weapons should have a penalty to the hit or damage chance as one is farther away from its target.
For each critter killed in this scenerio one can get a single improvement point. One Improvement point could be used for a skill, or use 2 improvement points to raise a stat.
Sorry about the randomness here I am kind of in a rambling mode.