Read the dependency statement
Look for wording that says the base game is required, or that the product cannot be played alone. Check the publisher's product page and the back of the actual box. A retailer's abbreviated title may omit the word expansion, and an attractive low price can belong to an add-on rather than a complete game.
Identify the exact required base product. A series may contain several similarly named games or editions. Shared branding does not guarantee compatibility. If the description refers to another expansion as well, include that dependency in the decision rather than assuming the first base box is sufficient.
Check what the expansion adds
Read whether it adds player seats, alternative modules, extra scenarios or material intended to mix permanently into existing decks. These are different purchases. More players may require additional table space; new modules may increase teaching; a campaign extension may be useful only after earlier content is completed.
Ask whether the addition solves a real need. If the base game has barely been played, more cards may make learning harder without improving the experience. A first session usually benefits from the published introductory arrangement. Extra content can wait until the group understands what it wants to change.
Confirm edition and language compatibility
Check component sizes, rules revisions and language, especially when buying older stock or used copies. An expansion may be mechanically compatible but visually different in a way that matters for hidden cards. Ask the publisher about uncertain combinations rather than relying on a similar cover image.
For a gift, verify what the recipient already owns and which edition it is. A photograph of the box and its product details can prevent an expensive mismatch. Keep any gift receipt or return arrangement relevant to the seller, without assuming every opened game can be returned.
A bundle deserves the same check as an individual box. Confirm that it includes the required base product rather than several expansions grouped together. Read the itemised contents and keep the edition information consistent across every part of the bundle.
