Not familiar with Game Rules off the top of my head.
Game Mode:
- is the ruleset for your game.
- Most games will probably have more than one of these, possibly a hierarchy of them in fact.
- Sometimes these are clearly visible and selectable by the player.
- Generally tracks what players are allowed to do and what the win conditions are.
- Common in Multiplayer games:
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Free for All
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Team Deathmatch
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Capture the Flag
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Conquest
- Common in Single Player/Coop games:
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Campaign
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Tutorial
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Sandbox
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Time Trial
- You can even use these in games where there’s not a selection, just to track what the player is supposed to do in a given area.
Game State:
- Generally tied to Game Mode.
- Holds information about the game world and progress toward win conditions.
Game Instance:
- Persists through map loads, server connections, etc…
- Used for any logic that needs to persist even if the player gets on another server or loads a different map.
- Think authentication information, in game chat, anything not tied to the game world itself.