I have a similar story to tell. As an undergrad in a course of robotics, we had to program a wheeled robot and all the robots would be place in an environment with obstacles. The robot should avoid crashing with the obstacles and the other robots. Extra points if the robots moved smoothly.

Me and my friend implemented a very simple algorithm. All the sensors measured distances to objects, and to every reading we would assign a vector whose direction oppose the one of the sensor and length, inversely "proportional" to the distance. Add all the vectors and move in this direction with a speed proportional to the length.

This turned out to work very well to avoid static obstacles and other robots. Most students implemented finite state machines. They crashed quite a lot and their movement was very clumsy, which I suppose was due to the fact that the transition of states was not very smooth.

To be fair, our success was a combination of luck and laziness too. If we had more time, we would have implemented a FSM too.