Interesting how language can be 'old' simply because of the increase in content available. In this case, the two words are compared, however the evolution time points are quite unique. Another reason to read between the lines.

Amplify’d from www.gamasutra.com

But having a rather provocative term such as "gamification" has put a spotlight on a category very closely related to "serious games." "Gamification," after only about year of existing, already has 552,000 Google references, while the at least decade-old term "serious games" has 770,000. Read more at www.gamasutra.com