Run is a 3D tunnel type game. You are in a four sided tunnel suspended in space with gaping holes in the floor, walls and ceiling. You need to run non-stop and avoid the holes by dodging or jumping. If you touch one of the walls the tunnel rotates so you are running on the wall. As you play the game and progress in levels you will learn that changing to another wall is a handy tactic.
You need to take advantage of the fact that you can change direction mid-air while jumping. You will also need to get the feel for making smooth jumps and get the timing down to allow consecutive jumps. Another thing you will notice is that when you move to another wall the game slows a little bit - that can be used to your advantage to get your bearings.
I found the game a little jumpy in Firefox, so I decided to try it in the Google Chrome browser. The optimized coding of Google Chrome made an amazing difference in game play. I had no jumpiness at all. I don't know if it was just the lack of jumpiness, or if it was a true speed increase, but the game seemed to run much faster. I found the extra speed to add to the fun, but it also made the game more difficult.