What if time was measured the way money was?
What if time had an exchange rate, like 1 US second is equal to .95 Canadian second?
It's not practical do this in real life, but it would be an interesting game mechanic.
Game currency is pretty constant, but what does change is the value of certain objects within the game. In the same way you can measure value with money you can also measure value with time. Objects can have a lifespan, your character can have a lifespan, the world can be running at a specific rate, events in the game can occur at certain intervals and last for specific amounts of time.