What are the key phases of the Game Development process?

The key phases of the Game Development process are: pre-production, production, and post-production stages for Game Development.

Pre-production is planning. At this stage, this involves the establishment of a Game Concept, a storyboard, listing technical requirements, and lastly the creation of a Game Design Document (GDD) that will provide necessary guidance during the project.

Production is the base. It includes coding, development of Art Assets and Level Design, adding sound effects. Testing is done at every step to ensure that every item works just the way it should work.
Post-production is the final testing, entailing the debugging and refinement of the game. This phase also prepares the game for its release and any updates post-launch that might need to be done.
At the same time, these stages guarantee that the development and release of a video game will be successful.