Oh, I try to stay away from games that don't address battery well. I had a game which I shall not name, and when I wanted to exit the game, I had to restart my iPhone, otherwise the game would run in the background and drain my battery dry.
Every time you have battery drain issue it's a bug that the dev should fix. I can see the AI working in the background on a TBS game but that shouldn't add more work load to the battery than a 3D shooter for example.