While not quite that simple, the rules for touch rugby are fairly simple.
- You can't throw the ball forward
- If you are tagged, you have to stop
- you score by putting the ball down in the tryzone
- If you go out of bounds, the other team gets the ball
There are no scrums, lineouts, mauls, rucks, kicking, etc. It's actually simpler than the vast majority of games played in any given gym class in America. If you'd like to take a look at it, here's the link for gym teachers who want to incorporate it into their curriculum: