Warning: OpenMOBA is IN DEVELOPMENT and NOT considered stable!
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OpenMOBA is an open-source RTS/MOBA engine which represents game worlds through constructive solid geometry (CSG) as opposed to traditional grid-based approaches.

Of note, OpenMOBA supports:

• 2D Maps (stitchable to form 3D surface-constrained worlds)
• Significant agent radius variation
• Arbitrary hole introduction into game world
• Arbitrary land introduction into game world (e.g. for bridges)
• Near-optimal Pathfinding (With configurable performance vs optimality tradeoffs)
• Iterative Pathfinding (Leverage prior solutions for fast pathfinding)
• Flocking
• Line of Sight Visibility Checks

You can play with OpenMOBA's sandbox by running TestGameTheGame.

Current controls are as follows:

• Right Mouse Button - Pathfind to Point
• Q - Test Raycast to Point
• Wall Introduction (Scribble lines, then introduce them as walls)
  • W - Add point to scribble path.
  • E - Remove last point from scribble path.
  • R - Submit wall introduction scribble as world hole (hold shift for permanent).