It's called dynamic lightning and blitz doesn't support that afaik, maybe you can calculate the uv coordinates where your lightmap shadows are and check if your player is inside the shadow area then tint the player's color...
Or you can use a dynamic shadow userlib like devil's child's to cast shadows from trees but that would be a huge performance hit.
Or you can use a dynamic shadow userlib like devil's child's to cast shadows from trees but that would be a huge performance hit.