EASY: These are games that are easy for beginners.
Advanced players would probably be bored with them. 

MODERATE: These games are aimed at intermediate players.
Advanced players might find them a little easy, while beginners would have a challenge. 

DIFFICULT: These are games that are easy for advanced players only.
Beginners and intermediate players would get frustrated playing them.

ALL LEVELS: These are games that are suitable for all level of players.
Generally, the difficulty of the game is based on your opponent. 

ANY NUMBER OF PLAYERS: These are games that may be played by any number of players, even odd numbers. Usually these games are better with more people. 

FAVORITES: These are games that many players find to be very fun.