Hi guys, new to the site, relatively new to D&D too. To summarize what this post is about; I'm a DM and my players own a dilapidated castle, which I want to work into the plot in a way that binds the player's characters together. I want to condense 6 months of game time into a single session, so we can skip ahead to the good stuff (i.e. you guys have an awesome castle and don't need to take care of daily business).
I'll try and give you all the details as concisely as possible. As a relatively new DM I'd love input and ideas from your collective experience, particularly about events during the 6 months.
Quick plot Summary:
The players banded together when they were falsely accused of rescuing a half-Orc barbarian from the Hangman's noose. The King took it personally and smacked a HUGE bounty on the players, leaving them no choice but to band together to clear their names (solving alignment conflicts and allowing characters to keep their backstory private). The players found enough evidence to clear their names and claimed the bounty, but were tricked by a shapeshifter who ran off with the cash, leaving them penniless. The King, pleased with the players, asked them to locate his ward, for which the PCs demanded land and titles in return. The quest completed, they became the owners of a dilapidated castle. Visiting it for the first time, a lycanthrope was showing them around when everyone was captured by a monster fighting ring, who thought they'd bagged a bunch of werewolves. Players break free, kill the werewolf, and start heading back to the castle. En-route they accidentally burned down a guy's bar, so he's coming with them to set up shop anew.
What is known about the Castle:
It's old and in poor condition. It is the oldest building in several hundred miles. They have been told that the castle has been built on an even older series of passages, leading deep into the earth. No-one has ever explored these passages, as they are filled with deadly traps.
Plot Hook:
Upon returning to the castle, a messenger from the King informs them that they have responsibilities, including gathering taxes from the surrounding land. The players are charged with getting the area back on its feet, and have 6 months to do so.
Starting Resources:
The barman that they are travelling with has an eye for business, and handles day-to-day things. They have their initial tax collection, and any money that they want to put into the pot. They have a small, untrained militia. They have access to people who can repair and build parts of the castle. They are popular with their people, having removed a werewolf that was bothering them. The barman will put his cut of the taxes towards fixing a tavern and restoring the stables, so the players don't have to do that.
Rewards:
Certain castle repairs will offer permanent stat bonuses. For example, a wizard's tower could offer +2 to Arcana, fixing the library could offer +2 to History, etc. Players will also get tax money and gifts depending on their decisions as leaders.
Gameplay:
I plan to run this by having 1-2 events per month. The following month, I'll update the players on events and the long-term impact of their decisions will become apparent. For example, if they don't have enough guards, then bandits will plague the land. All 6 months will be played in a single session, so events should be small enough to get through quickly.
Event Examples:
1) Thieves try to cheat a famous horse breeder out of his prize horse with faked documents. If the breeder's name is cleared, he'll give them fine horses as thanks.
2) The tax wagon is attacked en-route to the King. The players must deal with the problem by setting an example, otherwise the attacks will continue.
3) A nobleman refuses to pay his taxes.
4) Word has spread about the trapped corridors beneath the castle, and adventurers are breaking in, never to be heard from again.
5) The King requests a report about the land bordering you to the east. The players must decide how to gather the information.
Endgame:
The effective endgame is that the castle will become a link to more interesting adventures. By the end of the session it should be self-sufficient, so the players only need to check on it if they wish, or if the plot requires it. The players are free to pursue adventure without being held back by the castle, which would then serve as a base of operations for the party.
Thanks, looking forward to hearing your input! Again, I'm looking for general suggestions about the concept and ideas for what to do at each month interval.
-Dave
I'll try and give you all the details as concisely as possible. As a relatively new DM I'd love input and ideas from your collective experience, particularly about events during the 6 months.

Quick plot Summary:
The players banded together when they were falsely accused of rescuing a half-Orc barbarian from the Hangman's noose. The King took it personally and smacked a HUGE bounty on the players, leaving them no choice but to band together to clear their names (solving alignment conflicts and allowing characters to keep their backstory private). The players found enough evidence to clear their names and claimed the bounty, but were tricked by a shapeshifter who ran off with the cash, leaving them penniless. The King, pleased with the players, asked them to locate his ward, for which the PCs demanded land and titles in return. The quest completed, they became the owners of a dilapidated castle. Visiting it for the first time, a lycanthrope was showing them around when everyone was captured by a monster fighting ring, who thought they'd bagged a bunch of werewolves. Players break free, kill the werewolf, and start heading back to the castle. En-route they accidentally burned down a guy's bar, so he's coming with them to set up shop anew.
What is known about the Castle:
It's old and in poor condition. It is the oldest building in several hundred miles. They have been told that the castle has been built on an even older series of passages, leading deep into the earth. No-one has ever explored these passages, as they are filled with deadly traps.
Plot Hook:
Upon returning to the castle, a messenger from the King informs them that they have responsibilities, including gathering taxes from the surrounding land. The players are charged with getting the area back on its feet, and have 6 months to do so.
Starting Resources:
The barman that they are travelling with has an eye for business, and handles day-to-day things. They have their initial tax collection, and any money that they want to put into the pot. They have a small, untrained militia. They have access to people who can repair and build parts of the castle. They are popular with their people, having removed a werewolf that was bothering them. The barman will put his cut of the taxes towards fixing a tavern and restoring the stables, so the players don't have to do that.
Rewards:
Certain castle repairs will offer permanent stat bonuses. For example, a wizard's tower could offer +2 to Arcana, fixing the library could offer +2 to History, etc. Players will also get tax money and gifts depending on their decisions as leaders.
Gameplay:
I plan to run this by having 1-2 events per month. The following month, I'll update the players on events and the long-term impact of their decisions will become apparent. For example, if they don't have enough guards, then bandits will plague the land. All 6 months will be played in a single session, so events should be small enough to get through quickly.
Event Examples:
1) Thieves try to cheat a famous horse breeder out of his prize horse with faked documents. If the breeder's name is cleared, he'll give them fine horses as thanks.
2) The tax wagon is attacked en-route to the King. The players must deal with the problem by setting an example, otherwise the attacks will continue.
3) A nobleman refuses to pay his taxes.
4) Word has spread about the trapped corridors beneath the castle, and adventurers are breaking in, never to be heard from again.
5) The King requests a report about the land bordering you to the east. The players must decide how to gather the information.
Endgame:
The effective endgame is that the castle will become a link to more interesting adventures. By the end of the session it should be self-sufficient, so the players only need to check on it if they wish, or if the plot requires it. The players are free to pursue adventure without being held back by the castle, which would then serve as a base of operations for the party.
Thanks, looking forward to hearing your input! Again, I'm looking for general suggestions about the concept and ideas for what to do at each month interval.
-Dave