I've heard something about an Easter Egg. This factoid contains a slight spoil. Do not read any further if you do not want to know. This is JUST a hidden item in the game for those of you who hunt every inch of a game. The tagged skills are working correctly.
Skills costs more to increase the higher they get.
The following is the Skill Progression chart which is also in the readme.txt. Each skill increment from 1-100 costs 1 skill point. Each skill increment from 101-125 costs 2 skill point. Each skill increment from 126-150 costs 3 skill point. Each skill increment from 151-175 costs 4 skill point.