Game Design Document (GDD)

Pre-Production Milestones
• Pitch
• Concept
• Game Design Document
• Prototype

Pre-Production Deliverables
• As part of the Concept Milestone

Production Milestones

Production Deliverables
• Game Design Document

• Story Bible

• Scripts

• Art Bible

• Technical Design Document

Post Production Areas
• Maintenance
• Updates
• Support


I found another template which is from Chris Taylor: