Trophy Challenges are earned through a variety of gaming-related requirements.  Some trophies will present special rules which will define how a Challenge must be approached. 
These special rules are defined below and will be updated as new Challenges and requirements are introduced.


Rule: Pass the quiz
Related Challenge: Plants vs. Zombies
What it means:  This Challenge is completed not by playing for a certain amount of time, but for completing a quiz with questions about the game itself.  Extended details can be found in this FAQ entry.

Rule: Cameo Games
Related Challenge: Prime Time
What it means:  Two of the required games for this Challenge are merely cameos--they will only award credit on specific days.  You only need to complete the playtime for one of them to finish the task.  So, you can finish the "cameo" requirement by playing 2 hours of "The Apprentice" on Monday, Tuesday, Wednesday, or Thursday.  Or, you can also finish it by playing "Family Feud: Battle of the Sexes" on Friday, Saturday, or Sunday.  You can also play a little of each--if you played 1 hour of "The Apprentice" on Thursday, and 1 hour of "Family Feud: BotS" on Friday, you would receive the full 2 hour credit towards the cameo games.       

 
Rule: Prerequisite Challenge
Related Challenge: Around the Moon, Thanksgiving Feast, Fireside Gamer, Jewel Quest Heritage
What it means:  Before starting on this Challenge, you must have won the Prerequisite Challenge listed. 

Around the World is the Prerequisite Challenge for Around the Moon; if you have not fully completed Around the World, you cannot earn any credit toward Around the Moon.

Cookin' Granny is the Prerequisite Challenge for Thanksgiving Feast.
Comfy Quilt is the Prerequisite Challenge for Fireside Gamer. 
Jewel Quest Ensemble is the Prerequisite Challenge for Jewel Quest Heritage.

Rule: Play the games in the order they are listed
Related Challenge: Harvest Fest
What it means:  To win this Challenge, the required games must be played in order.  The second-listed game will not award any credit unless you have finished playing the first game for the indicated time. 

So, "John Deere" is the first game, "My Farm" is the second, "Magic Farm: Ultimate Flower" is the third, and so on.  Credit cannot be earned for "My Farm" until you have logged 120 minutes on "John Deere."  And you'll need 120 minutes on "My Farm" to earn credit while playing "Magic Farm: Ultimate Flower," etc.  Unlike other trophies, where games can be played in any order, or all at once, this type of Challenge requests you play in a specific progression.

This does not mean you have to play all 120 minutes in one sitting--you could play 30 minutes of "John Deere" this week and 30 minutes next week, and you would still have 60 minutes total credited.  It only means that until the bar is full for "John Deere," no amount of playtime will be counted toward "My Farm," and so on.