Puzzle (10000 programs)

Pros: Different settings for a range of abilities. Puzzles generated new each time.

Cons: Little challenge for expert English users. Some older users felt it was too child-focused.

Pros: Variety of questions. Time limit for each question. Play more than one game at the same time. Play with a random opponent or a friend from Facebook.

Cons: You can't talk to opponents. Only one level of questions.