First off, this game has tons of potential for some great use of creativity, unlike other genres where you can only add so much to the game for it to feel original (all shooters feel basically the same to me). I cant wait to see the "rest of the game" when more maps, demigods, items and strategic points on the map are added.
My point thus far is that we've only seen the basic stuff so having item ideas, demigod ideas are kinda useless at this point. Im also 99% sure that they are aware of the interface issues like lack of minimap, hard to target other demigods, hard to see whos on which team etc.
As for my idea (which you can guess from the topic title) is that some sort of neutral forces should be added. Not on all maps, mind you, but it opens up for alot more interesting map creation. I'll post a few examples of how Id imagine it to be used.
The cave.
Bases keep throwing waves at eachother like any other map. However, next to each base is a cave filled with beasts. The players can choose to push the waves and kill the opposing towers like they normally would on other maps, or form an expedition to clear out the cave. The cave should end with a boss of some sorts like a dragon. Finishing it will allow the players to take over a flag there which grants control of a gold mine and a portal which summons waves of lizardbeasts and a dragon to constantly stream out of the cave to join your regular waves. It should require mid-level heroes to clear the cave.
Breaking out!
Imagine a 3v3 map where one player on each team is cut off from the start position and imprisoned in a castle on one of two islands (one for each team). The imprisoned players has to make haste and fight their way out of the prison and take over a flag at the coastline of his island as fast as he can. This flag will capture a goldmine as well as create a bridge to the mainland for the imprisoned player to join up with his team and join the wareffort!
I will edit in more ideas later.