It's A Prequel
The most obvious change is that Lost Planet 3, despite its name, is actually a prequel to the first Lost Planet game. The not-so-subtly named world of E.D.N. III and its denizens—human, beast and mechanical—transformed quite a bit over the previous games in the series, and making Lost Planet 3 into a prequel gave Capcom an opportunity to explore a new chapter in the series without worrying about all the baggage that's been developed so far.
LP 3 concerns one Jim Peyton, a contractor of sorts who takes a job with the NEVEC corporation to send cash home to his wife and newborn. But he soon discovers that NEVEC isn't as benign as he had hoped. "He's discovering as he plays through this game that what they told him isn't really accurate to what he's seeing, Tunick said. "And as the game unfolds, you start seeing decisions have to be made on where he aligns himself."