CoreyCole: The pirate achievement includes getting the treasure *and* exploring every part of the Sea Caves. A few players have managed it, so it's definitely possible.
There are some non-working achievements that we're fixing in the first patch. Tomb Raider requires visiting a scene we removed from the game (oops!). Bossa Nova is possible, but requires killing two neutral "bosses"; we're taking those two out of the list.
We think Perfect Prowler is possible, but it is the hardest achievement in the game. Nobody has accomplished it so far.
In the very unlikely hope that you'll answer this question (instead of say "play it and find out") could you confirm whether perfect prowler could be accomplished simply by reaching day 50 without any combat, or whether all of the major quests need to have been completed, just without engaging in combat?
Because to my mind, the drat queen can't be peacefully resolved without the proach broach which as far as I know can't be gained without violence.