Intresting game! I managed to reach 22 level :)  

But after 20 lvl, when too many enemies, game start lag, so much, that I cant move recourses in minigame and achive new fances, camps or towers. 

Sometimes 2 recourses can be in one block at same time.

And sometimes even it is 3 in row, it didnt combine until I "shake" it.

For me, ability to remove/replace wood fances with stone or iron will be cool :)