Mombasa comes with 5 patterns built in, although you can add your own (See "Creating a Pattern"). The built-in patterns are called Towers, Tripoli, Dragon, Kilimanjaro, and Test Pattern.
Towers and Tripoli are the easiest of these patterns, Dragon is of medium difficulty, and Kilimanjaro is the hardest. While a score of 144 is possible on Kilimanjaro, it is very rarely accomplished.
Test Pattern is added for you to play around with. See "Creating a Pattern" for details.
When you first start the game, Dragon will be the chosen pattern. In the Pattern menu will be a list of all the built-in patterns, plus any patterns you have added. To change the current pattern, just choose the new pattern from the menu. The current pattern will be check-marked.
Warning: When you choose a new pattern, it cancels the current game and starts a new one.