Gaphor
An open UML, SysML, RAAML, and C4 modeling application with editable models, reusable elements, diagrams, and exports rather than a drawing-only canvas.
Why use it
Technical designers can keep component, interface, and relationship semantics consistent across diagrams for game-client and service architecture.
Where it fits
Use prototypes and playtests to find core experience problems while they are still cheap to fix.
What to check
Formal modeling requires shared notation and granularity, and over-modeling slows small projects; live collaboration and code generation are not its primary strengths.