Heres a quick low-poly model draft of the 'Boss Creature' concept, only spent about 1 - 2 hours on it so far  but i am pleased with the overall shape and proportions of the character. I just need to flesh out the face a bit and then the low poly version should be roughly complete after adding a full UV map to add the details.

I will then add more polygons to the mesh by using the subdevide tool, and then go in with crafting more detail into him and then a higher res UV map to create the high detail cutscene version.

Here are 2 progress screenshots of how the playable level is looking so far. In the first screenshot i have made prymatic planes and then sculpted them using the 'outline' selection tool and the brush tool in order to make them look like terrain. I have then sculpted 3 diffferent trees using a prymatic cylinder and extrudes / iron tool, then i copy and pasted them in different ways and edited them slightly to create a tree-lined walkway. The water was created by adding a very simple noise bump texture to a blue/green plane and then added reflection and a sky environment to it so that it reflects the surroundings and a realistic sky effect as water does.  Lastly i have modelled the 'bears house' concept that i uploaded previously and placed it onto into the appropriate place. 

In the 2nd screenshot i have now taken screenshots of the 3D trees that i modeled previously, attached the screenshots to 2D planes and then added some bump to create an illusion of a forest without using thousands more polygons (shown best at the bottom right). I have also created a basic effect of tree leaves by editing a plane using the brush tool and then adding a simple leave texture to it which is set to sphereical projection and tiled 15 times to add the scale. 

I am very happy with how the level is looking so far as it's my first attempt and is looking quite proffessional (in my opinion) for a low poly game.

Can't wait to put this to the test in Unity... where knowing my luck it will crash!