here is a quick and drty example, with some suggestions for animations of tree and background via moving tilebackground.
for each tree you need
variable start.x at the center of screen
variable start.y at some negative value
start.angle (random of 360)
and then you position each tree on elispe:
tree.x is start.x+cos(start.angle)*width.of.tree
tree.y is start.y+sin(start.angle)*(width.of.tree/2 or width.of.tree/3, or something else but les than width.of.tree)
set tree.angle to angle(start.x, start.y,tree.x,tree.y)
when you press left/right you add/substract value of start.angle for each tree - so each tree rotates
of course you add some vaule each tick to start.y to move trees down at some speed
here you go
look at my idea for moving background I think it would suit you game (by the way i like your game concept)