Half Life: Keller Experiment Catastrophe at Black Mesa

Dr Richard Keller is one of the top scientists in Black Mesa with Level 5 security clearance. His presence tho is known to create undesirable circumstances. Everyone in this part of the facility had suffered the unknown effects of either gas or extreme exposure to radiation, yet the effects on Keller: none. Was he just a witness to an experiment gone wrong or the Dark Mesa mineshaft hole was deeper and more sinister than we had thought