If a combination doesn't work the first time, then pick up the pin and drag the pin away and then make them collide while dropping the pin.
Explanation:
Because the pins are free-floating, they won't combine if they are simply next to each other. Otherwise, if two pins spawned next to each other, then they would automatically combine. Therefore, for a combination to initiate, a pin needs to move a certain distance before it is dropped onto/next to another pin. Well, either it detects distance traveled when being dragged or the magnitude of the impact between two pins, I can't tell.
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