> For the complete documentation index, see [llms.txt](https://castleoverlord.gitbook.io/whitepaper/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://castleoverlord.gitbook.io/whitepaper/about-the-game/why-play-castle-overlord.md). # Why Play Castle Overlord? * **Low Entry Barrier**. Anyone can play the game for free with limited features. Players can unlock the full game and earn rewards by owning at least one NFT trooper. * **Unlimited NFT Variations.** Each minting period offers a huge variation of new NFTs created by our talented artist. Every NFT unit is a combination of randomly selected parts that have their own color and design. These parts also come in different rarities that affect their appearances and in-game stats. The virtually unlimited combination ensures that every NFT is unique, and the limited minting period keeps the value maintained by scarcity. * **AFK-Friendly.** Players have the opportunity to gain resources both actively (assault battles) and passively (defense battles). * **NFT Added Value.** The value of an NFT in Castle Overlord is not only determined by its looks. Since every NFT is a playable unit, their battle capabilities are also part of the equation. By upgrading an NFT, it will increase in strength and become more desirable in the market. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://castleoverlord.gitbook.io/whitepaper/about-the-game/why-play-castle-overlord.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.