debug mode

Short definition from Wiktionary

Noun

1. 1
   The mode of a compiler or IDE that allows for debugging, with the availability of information such as variable names and line numbers from the source code.
2. 2
   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.