Interesting article in PC World on how playing games at work can be beneficial. http://www.pcworld.com/businesscenter/article/155284/does_gaming_at_work_improve_productivity.html
Red Orbit has a similar article - http://www.redorbit.com/news/technology/1610355/offices_use_video_games_to_raise_morale_productivity/
It still seems that the more interesting, innovative approach is to combine the two. One of the companies mentioned, Snowfly, appears to taking this approach. There still remains a custom element that can be challenging to overcome. Many areas of expertise for a given organization are unique – that's why people are hired to work, and so a generic game doesn't capture that uniqueness. However, there are other areas that are core competencies of all workers, and tasks that require those skills that can help the organization. These "organizational citizenship behaviors" are a far better place to build games than the unique "in role" tasks – not only from the emotional perspective of the employee ("why are you inviting everyone to come do my job with this game, am I not doing it OK myself?" , but also from a return on investment perspective. Productivity games do not have be expensive to build, but they are not free either.
Since most people probably just a game of Solitaire, then a spreadsheet and use Alt+Tab when people walk by the idea of a custom game to play to help the organization is probably appealing…