I am working out the advanced logic and interaction by applying it to different problems. Messaging the way the original Quake engine was set up is pretty straightforward. Half-Life 2's input-output system is interesting, but requires an additional mechanism beyond the existing keyvalues system. Lua allows some really powerful stuff. You could enter a string in the property editor, and the script itself could execute this string! But if it's confusing for me, it's going to be really confusing for an artist.

It's easy to make a button open a door:

-Set the door to be the target of the button.

-When the button is pressed send a message "Activate" to the door.

-The door receives this message and interprets it to mean that it should open.

How would you do the following in your favorite game engine, without scripting?:

Buttons 1, 2, and 3 can be switched on and off. Only when buttons 1, 2, and 3 are all turned on, a door opens.

Your ideas?

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