This app was mentioned in 5 comments, with an average of 11.40 upvotes
I play Empires and Allies, its a game by Zynga. The game is pretty well designed and borrows the best elements from Boombeach and Clash of Clans (troops don't die after every raid, and you can donate troops). Also has an option of resource donations which I find interesting.
https://play.google.com/store/apps/details?id=com.zynga.empires2&hl=en_GB
Very few games let you play for awhile without paying. I only take recommendations from others, finding games myself is a minefield in which 99% of the terrain is mines.
I would highly recommend Empires and Allies. It's one of the few games I can play for hours on end without getting bored or paying a dime. My phone's battery will die before I want to quit this game.
Command and Conquer + Clash of Clans, you say?
https://play.google.com/store/apps/details?id=com.zynga.empires2