From publisher blurb:
These solo role-play rules are designed to make use of Castles & Crusades SiegeEngine mechanics.
The rules provide oracles that fit in well with the games core dice mechanics, so you don't have to break the spirit of the game every time you call on the solo rules, it all feels like C&C.
There is also advice on playing published modules using the solo rules, making combat more narrative. Narrative Combat allows you to bypass all the roll to hit/roll damage for minor skirmishes that are normally used to set the tone of an adventure and to wear down a party.
Narrative combat makes these skirmishes more exciting and shorter.
There is also advice on getting started with solo playing, for those that have never tried it.