To unlock the "Hint" button type 50% of all possible words. Using most of the short and well known three and four letter words should be enough. There is no penalty for entering wrong words except losing time.
Easy "The Achiever" Achievement
To make it possible for 8 Letter mode, enter the "Options" menu and pick the radio button. You will now need some luck to obtain a puzzle that includes a 8 letter word. You can accelerate the search by consistently picking the "Pause" button, selecting "Restart", then inspecting your word finder.
Easy "The Graduate" Achievement
Although an eight letter word is worth the same as a three letter word towards your progress, you still need to complete the puzzles as fast as possible to advance on to the next one. Note: There are some words missing from the game's dictionary however it includes some non-English words (such as in Latin). Use the "Hint" button frequently.
Puzzle Solver
You must type 75% of possible words. Use the "Hint" button to reveal words from longest to shortest. You will also get extra time for any typed word with more time for longer words. Some of longer words are hint to shorter versions (such as their singular form). There is no penalty for entering wrong words except losing time.
Various Steam Achievements
Complete the indicated task to unlock the achievement.
Easy "Executive" Achievement...