I like to storm castles and I have hosted this battle many times using all sorts of different rules. I have learned some one needs to take the part of an umpire. The players should never know how many batter points a section has or even how much damage has been done. There is always hidden movement and reinforcements to keep track of. Some one needs to be able to make a decision in case rules are not clear.
Here the Giants and Trolls have breached the gate only to be trapped by the city guard between flaming oil and two towers full of archers.
The Troll and Giants never made it to the next gate. The attackers did not think to bring up the rams they left out side the gate.
The attackers make good progress against the lightly defended walls. The towers are able to blunt the attack until the siege towers are able to carry them by storm.The gate to the next level is on the other side of the fort so it is for nothing.
Here is a good example of why players should not know where and when relief forces are going to show up. This player left his force in place waiting for the counter attack he was sure would come. Even one of the units in support of the gate assault would have turned the attack into a major victory instead of a loss.
The defender concentrated his fire against the siege tower archers. You can see some of the fall back positions the defender will use to protect the keep and the first inter gate.
The siege rules in SBG should be treated as a guide line. You are only hurting your self by limiting your self to the Hobbit rule set.