In the original Age of Empires III, it's not important to earn large amounts of experience in the campaign (cheats), this is due to the fact the player won't be able to Build a Deck like in skirmishes. Any new cards unlocked will not be able to be switched out for inferior cards, so the player is stuck with both. Furthermore, if the player reaches the maximum number of cards allowed in a single age (9) the next card purchased for that age will push one off the list (can never be used again), maybe even one the player wanted to keep. This is no longer the case in Age of Empires III: Definitive Edition, where the player can use the standard deck builder interface.
The Knights start with 3 Commerce Age cards and 2 Fortress Age cards already selected for them. This means the player can only choose 6 more Commerce Age and 7 more Fortress Age cards before the player is at the age limit, and start pushing cards out of the deck if more are purchased for that age. It is safe to buy all Exploration Age cards with the Knights, if the player really wants them. The player starts with the following cards already selected:
2 Settlers and Crates of 300 Food
8 Crossbowmen, 6 Rodeleros, Native Lore
1 Falconet, 1 Covered Wagon
If the player is playing on easy or normal difficulty and wish to destroy the The Circle base at the end of Act I: Blood it's important to take both Falconet cards.
The Heavy Fortifications card is the only way for the Knights to upgrade their Outpost to Fortified Outposts and their Fort to a Star Fort.
The Royal Decree to Claim the New World card is the only method that enables the player to improve the Hoop Throwers.
The 8 Crossbowmen card used to deliver what it advertised, but since an update[When?] in the Definitive Edition, it has been rendered useless, and requires mods to function properly. This is because the root card used by the playable civilizations was updated to accommodate the Ordenança Riflemen and Landwehr upgrades.
Trivia[]
The '5 Lancers' icon suggests the card sends 6 Lancers, while in reality it only sends 5.
Increasing the Home City level also increases the deck size limit, which can go beyond the number of cards the player can place in the deck (10 per age maximum, so 40)
The '1 Falconet' and '2 Falconets' cards both have a purple border, but cannot be sent infinitely. Note the missing infinity symbol in the top left of the icon.