Two guys and one girl are jumping on black cardboard in the middle of the forest.
The kids are imagining that they are on a treasure hunt.
The fact that they are imagining shows that they are playing, but this was not clear in the first sentence.
exists e1 s1 x1 x2 x3 x4 x5 x6.(n_forest(x6) & n_middle(x5) & in(e1,x5) & of(x5,x6) & on(e1,x4) & n_cardboard(x4) & a_black(s1) & Theme(s1,x4) & Actor(e1,x1) & v_jump(e1) & subset_of(x3,x1) & n_girl(x3) & card_eq_1(x3) & subset_of(x2,x1) & n_guy(x2) & card_eq_2(x2))
exists e1 p1 x1.(n_thing(x1) & n_kid(x1) & Topic(e1,p1) & Actor(e1,x1) & v_imagine(e1) & exists p2 x2 x3.(on(x1,x2) & n_hunt(x2) & of(x2,x3) & n_treasure(x3)))