True story - In the year 2000, I attended a lecture at the University of Michigan on collision avoidance. I wanted cars to be able to target other cars in the demolition derby game I was working on and not accidentally run into the wrong car. After the lecture was over I saw Matt Toschlog (of Parallax Software and one of the creators of "Descent") and he asked me a very appropriate question - "Why are you worried about collision avoidance in a demolition derby game?" I quickly forgot everything I had just learned and no one ever complained that the cars collided too much.
I am back working on a new version of the demolition derby game 15 years later. I am currently doing a Kickstarter for it. I promise there will be no collision avoidance in the game.