Exploring the entire map (Wanderlust) appears to be, by far, the most difficult Steam achievement for me. Just can't trigger it and I've been completely out of clues 5 map run-thrus ago :
I completed all achievements in the game and figured I might as well post my final team and answer any question anyone might have. This was an amazing game. : r/MonsterSanctuary
Steam Community :: Guide :: The Keeper Master's Achievement Guide
Monster Sanctuary - Trophies and Achievement List | gamepressure.com