Kickstarter exclusives are rewards given only to backers during the campaign. This means, if you purchase the product outside of the Kickstarter campaign, the Kickstarter exclusive items will not be there.
The debate of whether to include Kickstarter Exclusives into your campaign is quite a hot debate. There are pros and cons to both sides of the argument. I will not say whether they are good for bad, but will detail the positives and negatives of both. I have seen many campaigns (both successful and unsuccessful) use both options. Hopefully from this information, you can decide whether they are right for you or not.
There are two types of Kickstarter exclusive items you can give: Gameplay and Component.
Gameplay Exclusives are items that change the gameplay in some way. Whether this be additional cards, miniatures, or rules, it is something that adds or changes gameplay compared to a retail game.
Component Exclusives are items that are added to the game that upgrade the components or parts of the game. They can also add functional components, for example a game board or card holders but these should not important to the actual gameplay.
Out of the two types of exclusives, I personally think component exclusives are better. Lets have a look at the pros and cons for using exclusives.
Having Kickstarter Exclusives
1: Reward backers for helping you fund the campaign during the campaign rather than at retail.
2: Gives incentives for people to come back the campaign and add extra money.
1: Split your buyer base. If you Kickstarter exclusives you will have two different products with potentially different experiences (mostly with gameplay exclusives). This may annoy some people who want everything in the game.
2: Backers will purchase exclusive items to resell later at a high cost.
3: Potentially higher manufacturing/shipping cost if you have multiple versions, additional parts, etc.
No Kickstarter Exclusives
1: Do not split your potential buyers and backers. People want everything in the game. If you have exclusives, people that find out late about the product may be disappointed and not purchase the product.
2: Less manufacturing and shipping hassle.
1: Backers have less incentive to back your product now. They may wait for retail.
There are many pros and cons to having and not having Kickstarter Exclusives. If you are thinking of adding them, I would recommend non-gameplay exclusives. It will reduce the annoyance of people who did not know about the Kickstarter and no can’t get a full product for normal price (higher resell). And at the same time, it will still give a nice exclusive reward to backers.