From the introduction:
Creeks and Crawdads was originally published by M. Martin Costa in 1986. It's a fun little game, especially in concept...[but] the game mechanics, while functional, are very 80's in style (unsurprisingly). The rules are very firmly rooted in their wargaming and D&D ancestry - an unfriendly and overly complex combat system.
[Creeks and Crawdads (Impact System)] is meant to be an entire replacement for the original Creeks and Crawdads game.
The Impact System version of the game retains the D6 dice pool of the original, but collapses the original nine Attributes to only four (Fighting Ability, Intelligence, Tool Use, Awareness) and overhauls the core mechanic to be much simpler. This allows a focus on the strengths of the quirky game concepts.