User stats for november (google play and flurry):
19,475 installs
176,090 sum of daily active users (i’m summing active daily users from every day in november)
Median session length: 5.5 minutes
Total time spend in app in november: about 13 years
Well for one your Banners seem to be giving your a terrible eCPM. Based on your information your Banner eCPM is $0.12.
Try experimenting with different refresh rates and placements.
One thing I can recommend is to not have banners displayed constantly. The user can easily become non-attentive to something that is persistent and isn’t part of the game. Try to include some areas of the game where banners don’t show. That way, when they are presented to the user they become a new entity on the screen and will be more likely to draw attention. In general practice the trade-off between CTR and loss of impressions should be worth the while.
Where are your users based? If your users are from low paying geos then your eCPM will likely be low. Not much you can do to change these factors without marketing and advertising, but is your users are based in EU/U.S then something is wrong here.
Also, try using a network that specializes in games, like AppFlood or HeyZap. You may get better results than Admob can provide.