I recently watched some footage of I Am Setsuna from E3.

Here’s my analysis of the evolving state stack, as you play this spritual successor to the classic RPG Chrono Trigger.

Map and Dialog

There’s likely a catch-all map state in which characters can run around, interacting with the world by opening chests, entering doors and new areas, and talking to NPCs.

The gameplay starts in a snowy forest. So, there’s a Map state pushed onto the state stack that has a reference to the map for this snowy forest.

| Map |

As the player wanders around the forest, the player encounters talking NPCs. These NPCs likely have triggers that push a Dialog state with a reference to the NPC’s dialog onto the stack.

| Dialog ←PUSH |
| Map          |

As the player advances and completes the dialog, the player is returned to the previous state, the snowy forest Map.

| Dialog →POP |

| Map |

The gameplay is controlled by the current state at the top of the state stack. This provides a more convenient way to track the appropriate controls and UI elements than to sprinkle a bunch of complicated conditionals throughout some monolithic game code.

Next time I’ll talk about combat.