Mechanic/encounter tweaking

[duckinator]

• https://en.wikipedia.org/wiki/Dynamic_game_difficulty_balancing
• https://en.wikipedia.org/wiki/Flow_(psychology)
• https://en.wikipedia.org/wiki/Strafing_(gaming)
• https://en.wikipedia.org/wiki/Crowd_control_(video_gaming)

[duckinator]

• http://www.fullbrightdesign.com/2009/02/basics-of-effective-fps-encounter.html?m=1