So let's take your standard football field, and then cover the whole thing with a flat foam pad. Let's take lots of foam and put in walls 3-10 feet high. Let's put giant foam blocks on the field to make it uneven. Let's also add some steel poles with ropes hanging off of them that players can swing on. Some of the foam blocks are anchored, but some aren't, so some of the more sophisticated strategies can involve some of the teams moving blocks around.

I'm not sure how to assemble these things on a field, but wouldn't this make football more fun to watch?

We'd also have to change the rules, I guess. Every score would have to be a touchdown, but a team would get different amount of points depending on where on the endzone the touchdown was scored. Instead of a free kick, the team coach would choose a time (less time gets the team more points) and a member of the team, starting from a certain position on the field, has to carry the ball to the endzone in the selected time. To make this kind of time selection work, now we need to have fractional points.

Also, players should be able to roll on landing, so for a player to be down they would need to be in contact with an opponent.

There should also be handles on the ropes so players can hold on to them while holding the ball, and weights on the ends so that the player with the ball can grab a rope swung up to him by a teammate.