The first 4 chapters are the actual story and not grindy. The 5th chapter is kinda repetitive and is really only for the new war mechanics.
Leveling is the only grindy part of the game because to get XP you have to do the orc missions and the XP scales with their level so you need to basically...
It's most likely that the person that had it before didn't redeem it. Nintendo probably just has it there as a disclaimer in case somebody already redeemed the registration code.
[H] Metro 2033, Risen, and Sacred Citadel Humble Bundle Steam Key
A Red Faction Armarmaggedon Steam Key
[W] To trade for something just send me a pm I have no idea what anybody would like to trade for this.