Ambition Mode is the extra game mode in Dynasty Warriors 8, where players begin as lowly officers and are tasked with building the Tongquetai Palace, which will bring the Emperor to your town. This is done by participating in battles to gather materials, gain fame and recruit new officers.
Battles are divided into three different kinds, which are Skirmishes, Unconventional Battles, and Great Battles. Skirmishes are very small battles where the main focus is on collecting materials, Unconventional Battles are for gaining fame and Great Battles are where you can recruit the highest number of officers.
There is another type of battle, which only appears after clearing 2-3 battles in a row. At the end of one of the above kinds of battles, you get the option to either return to your camp or go to the next battle, which is slightly more difficult than the previous one. Once you participate in 2-3 consecutive battles, you will see a Duel appear, which is a large-scale battle where you will find the playable officers, who join you upon defeating them.
You being Ambition Mode with your only facility being the Blacksmith. The game will automatically build new facilities as you recruit a set number of officers. For example, the Teahouse is built once you recruit a total of 3 officers. These facilities have their own services, such as the previously mentioned Teahouse selling food items that give you temporary buffs in the next battle.
These facilities can also be leveled up by using materials found during battles. There are two different kinds of materials, those for facilities and then those for weapons. You can tell which are which by either going into the Camp Management option under the pause menu or at the results screen at the end of a battle. Leveling up facilities will make them offer you new services or even better ones, such as the Teahouse offering you better items.