Arcade Typing Tutor 1.1.8 has a nice graphics implementation of an old idea that appeals to the arcade gamer, especially boys learning to type. It really isn't a tutor in that it only develops speed skills by increasing the rapidity of words with higher levels in the game. I've found also that the game freezes regularly in Tiger (10.4.2) much to the annoyance of those playing.
The fixed scope of the vocabulary and thus the keys used is a major drawback to learning to type. Although the user can create a separate file with custom letter combinations and words (as noted in the readme file), this could be updated easily. For example, it shouldn't be hard to create a sequence of letters or words that would improve keyboard coverage beginning with the home row and moving up into numbers and special characters. It would be nice if the letters used became more complex at each level, or if there were a choice of which group one could practice with on the keyboard.
This is one of very few arcade style games for the Mac that can appeal to beginning and experienced typists both, but it needs improvement.