Groups of minimum 8. If you have a couple of spares you can have groups of 10, but pull the cones out a little and have (6 v 4) instead of (5 v 3). Choose 3 defenders (or 4 for group of 10) who can only run in the outer square. Attackers take one side of the square each, plus one in the middle.
Coach gives the ball to the attackers. On 'go!' the player with the ball (e.g. B in diagram) must find a team-mate, either on the perimeter or in the middle.
Players on the outer cannot enter the square, but can run around the perimeter to receive.
Defenders run at the player with the ball, who must dispose of it before they are tagged.
30m is quite a long distance for defenders to cover, so focus is really on decision making under medium pressure.
Attackers run the lines of the square so they have space and ball-carrier doesn't need to kick around corners to hit them.
As you'll probably have numbers for 2 groups, introduce some competition between the 2 squares by having each attacking team call out the number of consecutive kicks they've made.
The contest ends if a turnover is effected, or a kick goes off the line of the square, e.g. over the players head, or tumbles past the player, or the player with the ball is tagged.
Team with the highest consecutive kicks wins.
Rotate defenders and restart.