Secure and efficient networks

The Defender builds a connected network. Each link creates 2 units of value and costs the amount shown above. Every node's value equals its number of links. Net value is network value minus connection costs, before any attack.

The Defender protects one node and the Attacker targets one node without seeing that protection. A protected target blocks the attack. Otherwise, the Attacker earns the target's value and the Defender loses twice that value (ρ = 2). Damage does not spread further through the network.

Each round is a new encounter on the same network. The Defender's payoff is network value minus connection costs and any damage. The computer chooses its move before you commit yours, using the encounter equilibrium. Hints are optional.

When you play as Attacker, the computer builds the best of the candidate network structures in the paper. Above 13 nodes, this is a candidate benchmark whose global optimality has not been verified.

Drag nodes to rearrange the graph. Click two nodes to add or remove a link while building. Keyboard selection works with Tab and Enter. Hover or focus on a node to see its value. Moving nodes changes only the layout. For larger networks, scroll the board.

Game settings, networks, protection choices, targets, outcomes and hints viewed are recorded to study how people design and protect networks. A random session identifier connects your rounds. No name or email is requested.