So this is quite a large read but it presents some really interesting research that looks into gamification and the impact of games at work. The study looked specifically at the effect of gamification on two variables, positive affect and performance of employees. It managed to get results from over 200 salespeople and had some interesting findings that included an increase in positive affect at work when games were entered wilfully. When consent of gameplay was lacking though it was found this led to a decrease in positive affect and to an extent performance as well.
Citation: Mollick, Ethan R. and Rothbard, Nancy, Mandatory Fun: Consent, Gamification and the Impact of Games at Work (September 30, 2014). The Wharton School Research Paper Series. Available at SSRN: https://ssrn.com/abstract=2277103 or http://dx.doi.org/10.2139/ssrn.2277103