Recently, while forced to siege with just ladders, I manged to push up the ladder and get on to the wall, but the rest of my soldiers struggled to get up and get a foothold... I was too outnumbered to be able to help clear the way and the dumb AI was struggling to get men on the ladders so no chance of overwhelm the defence on the wall, men just trickled up the ladders to certain death.
I managed to go round the wall, drop down and go around to open the undefended gate, letting all my men charge through the main gate and trounce the defenders with minimal casualties.
Got me thinking: it'd be nice to have some roguery/tactics dependent sneaking similar to this. Perhaps a stealth mission (kind of like hideout missions) where you lead a small group against the unaware defenders and sneak up over the walls to open the main gate or break enemy ballistae or mangonels to make the main attack go easier. Obviously there is a risk factor involved with the mission, as once the smaller patrols/watchmen detect you, they can sound the alarm to spawn in the rest of the defenders, meaning you would have to escape or get the gate open before getting swarmed and captured/killed. Once the gate is open, the player can choose to spawn in the rest of their army, leaving the infiltrators to defend the gate until the rest of the army can reach them, less the defenders bar the gate again.
Tbh, even a %success check of actions like disabling enemy siege or opening the main gate before battle, tied to the roguery skill, would be a nice alternative to bombarding the enemy to oblivion or bumrushing the walls.
This could be balanced fairly easily. As a success check, obviously there is a chance of failure which will lose all of the soldiers you sent and achieve nothing; also maybe not all objectives may be achieved (e.g. only 3/4 ballistae were sabotaged); it'll only work once per siege (as they'll be on higher alert now) and defenders will rebuild sabotaged engines as they would if they were destroyed by bombardment, so it only makes sense to do it right before an assault; success in opening the main gate could also still fail if the defenders are able to overcome the small force holding the gate once the actual battle commences.
The mission version would be high-risk as you could be captured and your army disbanded if you fail. The most difficult part would be balancing the stealth element and response times of the garrison once alerted. Maybe higher roguery skill could cause more latent response time if alerted, or a lower number spawned in? Or just less guards on the wall (as those with higher roguery are more likely to know when/where there are the least guards. Garrison size could also impact this, making it more practical but risky strategy for small armies sieging lightly-defended settlements which can't sit around all day bombarding as Monchug will inevitably show up with <800 horse archers, and more of an unnecessary risk for large armies.