I made what appears to be a mistake by "picking locks" for some of the doors when I started out on my quests in Puzzle Quest 2. Am I going to need to start over with a new character and bash all of the doors in order to get the Gate Hacker achievement?
Unfortunately, you will need to start over with a new character in order to get the Gate Hacker achievement. You have to choose "Bash" on all gates, doors, and chests in order to receive it, even if they have other opening options. You receive credit for the achievement after you complete the game, not after you bash the last door.