My classes love to play tag games and this one adds a little extra fitness:
Divide playing area in half using cones to mark dividing line. Use 2 cones in each area to mark a “door”. There is a tag game going on in each area. If a person is tagged, they go out of the door in the gym-half they have been playing in. They complete 10 jumping jacks (or any fitness task you designate) then enter in the door of the adjoining game and play in that game. I designate 3-4 children per game to be “it”. They use a yarn ball to tag. Every few minutes, I blow a whistle (students freeze) and trade students who are “it”.
Most tag games work better outside, but this one seems to work well in a gym space. We were driven inside today due to wind and my students loved playing this game.