Walls and hills gap

[Wesley]

One of the problems I see with the game is that walls both types don't go up 30 degree slopes in hills but units can. So I get gaps at the hill edges. is that a known issue or am I missing something.  It is usually these gaps that allow the enemy to bypass defences and rush early. Perhaps another form of wall buildable on steep slopes. Spiked abutment. Lower hit points than a wall but can only be built in 30 degree slopes and hill terrain. Stops enemy rushing around the wall hill gap. Yes I'm a turtle, so shell me. 

Even on easy we are not able to get deep into the game because the AI can build nothing much but troop /workers and then russh. The troop worker idea is valid it we can counter that early game defeat. I notice most of the games on youtube are on sandbox mode.