off the top of my head you/kids can make horse stick toys.
draw/print horse heads on card board sheets and glue these on one end of broom sticks (you can unscrew them). you can make horse mane out of black felt fabric, or just include it in the cardboard cutout.
the kids can have a horse race with those.
here is a pic of a toy horse stick
dunno about the georock thing.
maybe they can aim the spears toward a box. each kid can write his/her name on their allocated spears, whoever ends up with the most number of spears in the box gets a prize. i do not think it is a good idea for them to associate spears with an "enemy" at this age.
re: fish and prophet musa, alaihi assalam, what would be the moral of the game?