Help with trees

Help with trees

Hello, Im currently making a game. And to start of I wanted to create a jungle. But im not sure what to do. As I need a ballance between visible + walkable space and not visible or non-walkable space.

 

Im using an angle like pokemon.

Here's a picture

I want to be able to see the player and the ground. But I also want to show where people can/can't walk in a dense jungle area.

(Dark green patches are jungle leaves -- The places where there should be trees)

If anybody knows what to do please tell me. (I am not asking for sprites, just advice or examples)

 

Thanks in advance!