Win Fast Money in 10 Challenge Mode games playing alone.
Playing alone means without any other controllers against the AI. You will need to beat every theme on every difficulty for all of the achievements in the game. You will get this achievement going for all other achievements. You will need to win a minimum of 46 Fast Money rounds anyways, so this will just come along with those.
What is Fast Money?
Fast money is the last round of the game. You must have more points than your opponent by the end of round 4. Once you win that part, you will get asked a series fo questions much like the normal ones. This time you just pick 2 answers for each question (5 questions total). To win, you must have 200 points or more. This can be extremely easy or tough, depending on the questions and how split up their answers is. Difficulty does not seem to matter with this mode, as you have no competition.