Castle Yard Entrance thing

So yeah, i've been working on a level for my game where all it is is an entrance to a castle. So I guess you could call it a courtyard? Basiclly the player will be stuck in this courtyard while waves of monsters come from the front entrance. So the player has to kill all enemies until the levels boss comes. So my idea was to make it a small, yet large enough level that keeps the player in bounds, but allows them enough freespace to run and hide in a corner if they have to. This isn't done yet. It's what I have so far. I still need to add a busted up front door, and a door (just for visual display) behind the tree aswell as many side objects to add detail to the game. But this is what I have so far.
I am going to add quite a bit more. But let me know what you think so far.