Having a quarterly game allows everyone to reflect on all of what was or was not accomplished that particular quarter. Regardless, there should be some form of celebration for all of the progress, successes, and hard work made despite whether or not someone hit the 100% mark. This type of event/activity will positively reinforce the efforts that were made, and likely inspire and or motivate others to improve in some way next quarter. It also gives you an opportunity to showcase how understanding, supportive, and fun your business environment can be.
Try to make the game somewhat relevant to the objectives you had for the quarter.
Try to give the name of the game something unique, clever, and that will stand out!
Make sure that the target is somewhat realistic, so that regardless of whether or not someone was able to get 100% on their OKRs for that period, they will at least be able to experience a sense of accomplishment from completing the game's objective.
Be thorough when writing out the game's description.
Make sure the rules are clear, concise and easy for everyone to follow along!
Finally, make the celebration fun and engaging! Don't worry about making it expensive as there are lots of free ways you could choose to celebrate like playing a game, or ordering a pizza.
Implementing a quarterly game gives you an opportunity to get everyone involved, break up the regular workflow, and add something different into the day-to-day workflow.
Here's an example: