Citadels is a fantastic game that continues to age well. I find my collection is often a healthy mix of new and exciting games as well old and time proven titles. Both can be amazing. In the case of Citadels, with a reprinted edition with more and updated roles, you can have both.
Citadels can be played in 30-45 minutes, and accommodates variable player counts, shining at 4-6 players. The game teaches in 10 minutes, and playing a single sample round will give everyone at the table a good feel for the game.
Citadels is a role selection game, a game where players take turns secretly selecting a role although there tends to be enough information at the table for some players to make better educated guesses at who picked what. Once all roles are selected, the game goes through each role one at a time, giving each player the ability to enact their turn along with the specific benefits of their role. The goal of the game is to complete your city, and then score based on what's in your city, special bonuses, being the first to complete and more.
The game has just enough 'pull down the leader' to keep everyone invested, without being so much that it's annoying, but where the game really shines is the role selection and how it plays out each round. Some of the roles give you extra income, but the really fun roles screw with other players. If you pull the Assassin, you get to designate a role, and that player doesn't act that turn. Now keep in mind, you're not designating a player, you're designating a role. A role that may or may not even be in play. Or perhaps you'll take the Thief, and steal from another role...but again...will you? And does that player even have any money? Or perhaps you want to take the King, so that you can act first next round. But the prior King may have chosen Assassin, and has now killed the role of the King preventing your coup.
The game is fun. It has just enough light screwage to pull players in, without so much as to turn off players who don't like in your face games. It's affordable, accomadates multiple player counts well, teaches easily and is just plain fun. Citadels is a worthy addition to any collection. Not as the meat of your gameplay, but as a solid appetizer that will generally please.