Hey Ross. Long time watcher, first time poster. If you like RTS games, and you can find it, check out "Impossible Creatures". It is my favorite RTS of all times. It is also really hard to find now. When you said you enjoy customizing your army it made me think of this game. You can combine 2 animals to make your units. You can make, lion-sharks, chameleon-whales, electric eel-hornets, or any variation of any animal in the game. You decide what parts you want from the two animals.
Here is a game play demo of it:
