I believe the last game themed tree the wife did was way back in 2011. She surprised me this year with a Green Hill Zone inspired Sonic Tree.
It's sort of subtle, compared to previous gaming trees she's done. The checkered ribbon is inspired by the checkered turf of the Green Hill Zone, and there are gold rings, Chaos Emerald'esque gems, little Sonic character figures, etc.. She said the Blue and Yellow balls were supposed to represent Sonic and Tails in spin mode, which I thought was a bit of a stretch, but still sort of a cute thought.
She had a red paper ball 'thingie' on top that was supposed to represent those checkpoint marker switches that turns from blue to red, but I decided my gold prop ring would make a better topper, which she agreed. Sadly, we had to leave the tree lights off everyday until Christmas because our youngest two cats are drawn to the lit tree like a moth to a flame. They brought the whole thing down in the middle of the night on the night she put it up. Little creeps.