Hot reload
Also said as Live coding, Hot swap
Changing code or data while the game keeps running, so the new version takes effect without restarting or losing your place.
Feel gets good through hundreds of tiny adjustments. If each one takes a minute of recompiling and walking back to the same spot, you make far fewer of them, and the game is worse for it.
Say it
“Let me change jump values while the game runs. Watch the tuning file, reload it on save, and keep the player where they are.”
Where you’ve seen it
Naughty Dog's GOAL language, written by Andy Gavin for Jak and Daxter, let a programmer edit a function, recompile it and insert it into the running game without restarting.
Not to be confused with patch
A patch updates a shipped game for players, and usually needs a restart. Hot reload is a development tool, for one person trying things at their desk.