This is a comprehensive hacking guide for the US version of Contra on the NES. This document is meant for hackers and programmers who are interested in learning about the inner workings of Contra.

The document covers these aspects of the game:

• Level headers
• Graphics
• Level data
• Blocks tile mappings
• Blocks palette mappings
• Enemy data
• Sprite data
• Compression algorithms

The ZIP file also contains a companion document named “Enemy Attributes”, which contains all the details about how to modify enemy attributes and how they affect their appearance and behavior.