How, in a game, could we create a Symbol that Takes on Increasing Emotional Associations and at the same time make it a Usable Symbol (something that has a function in gameplay)?
Let's say you're designing a game with a Tolkien-like story. (Yes, it's overdone, but we're just using it for instructional sake.) You play a relatively powerless Hobbit-type, going up against a fearsome enemy with supernatural powers.
Your motivation for undertaking this heroic quest is that the villain wiped out your family. It's your responsibility to both seek revenge and stop the villain from killing other innocents.
Before he died, your father gave you a pendant with your family crest, which had been handed down through the generations. The first time we see the pendant is in a cinematic, when your father gives it to you as he lies dying. So it is associated with love.
As you go on your quest to bring down the villain, you can recharge your life force (if you don't do it too much) by bringing out the pendant and clenching it. So the pendant comes to also be associated with life.
At some point, you need to permanently (or so it seems at the time) give the pendant to a fallen, dying friend to save him by recharging his life force. So now the pendant is associated with self-sacrifice for a friend.
And if the pendant eventually comes back to you and gives you a decisive super-boost of life force for the final battle, it would then be associated with victory.
Although it would operate outside the gamer's conscious awareness, this would be a Symbol that Takes on Increasing Emotional Associations and it would add emotional depth to your story.
Because the pendant plays a role in gameplay, however, it's also a Usable Symbol, serving double-duty (enhancing the depth of emotion but also serving a function).