Setup. Keeper in goal. A server wide. Three or four players in the six-yard box holding tackle shields, pads or just standing firm.
How it runs. The server crosses. The players in the box hold their ground and lean in, without jumping. The keeper calls, comes through the bodies and catches at the top. Any ball that is dropped is live and the nearest player shoots. Four crosses from one side, four from the other, then rotate.
Make it harder. The players in the box may move before the cross. Then one of them is allowed to jump with the keeper.
With 4 keepers. Keeper, server, two in the box.