Check it out here:
http://www.officeriot.net/hexwars
Currently you can buy coins and unlock units with those coins.
You also level up and unlock some units for free.
I think this is not working cause I havent made a cent.
I bet my players dont even know there's a shop... I have to make it visible for them.
So I'm considering giving coins to the players instead of unlocking the units directly.
This way players have to go to the shop to use their free coins, and in the process they might buy some coins...