Sentence:  A "<WSD>debug mode</WSD>" is a broad term used to describe a feature or series of features included in a game by the development team to allow quick testing of the game's various features. 
Meaning of the word marked with <WSD> tags:  A (usually hidden) tool or set of tools in a video game used in its development and testing, the use of which typically enables players to cheat, modify the game's behaviour, or perform diagnostics.