The first thing I noticed was that you can turn the AI players off in settings and play by yourself. I set the game to hard and it starts you off with 3 turns. Actually spinning and/or buying vowels won't make you lose a turn, but guessing an incorrect letter, bankruptcy, and lose a turn will deplete your turns.
The neat thing is when I finished the session, I got the achievements for Hard, Normal, and Easy, along with other misc. achievements.
* I only solved one of the puzzles correctly. The rest I ran out of turns and weren't able to solve. So you definitely don't have to win all of the puzzles. You might even get away with just winning money at the Toss Up but I can not confirm this.
ENJOY!