Now that the holidays have passed and my players are (mostly) available again, we've scheduled the first session of the year for tonight. I will continue running b/x - despite my liking some of what I saw in the 5e starter set, I have no reason to change systems.
The campaign began as an open table and ran that way until September or October. It took one session with a random player who, perhaps unintentionally, nearly sabotaged the party's plans to form an alliance with the rat people of the third level, to turn it into a closed group by December. The group is solidly 5 players, plus invited guests. Currently the party with hirelings and charmed creatures is some 8 or 10 strong, depending on whether you count the charmed white ape, waiting for the party to return, and the tanner who acts as the party's fence and handles sign ups for the adventurers guild they are forming.
The campaign has had its ups and downs in terms of my feelings about the sessions. Much of it, I think has been that I have been on my heels often trying to keep up with their plans and machinations - but as I am finally getting ahead of the party again on that front (in terms of the dungeon at least), I'm hopeful that i'll be able to find a grove that works for me. On the plus side, I am happy with how much freedom the players have, and that they take advantage of it- in addition to the adventurers guild, they now have some merchants working with them, and they have sent forth for engineers to submit their bids to rehab the tower above the dungeon, with an eye towards making it their home base. Even tonight they will probably spend their time trying to stop some cultists from opening up a portal to the Abyss and bringing forth Abaddon's diabolical army, rather than exploring further into the dungeon.
The cultists, and their raiding bandits, were to be a minor encounter to alert the party to the presence of an entire section of the dungeon that they were unaware of. However, the first few times, they showed no interest and that was that but of course, the raids continued, prisoners continued to be taken. A chance wandering encounter roll brought the cultists to the fore again, and this time, with evidence of prisoners recently captured and brought below, they did a little investigating and became incensed by what they found (some of my more gory/twisted descriptions, more at home in a Lamentations of the Flame Princess game).
The party has their work cut out for them: it wouldn't be so bad if the high priest of the cult hadn't turned into a salamander (in b/x a fire elemental lizard thing) that retained his previous form's powers, although he's gone a bit mad as a result of the transformation.
When we left off in December, the party was in a bit of a panic about how to deal with this unexpected threat. I'll give them some time tonight to make sure they dot their i's and cross their t's to their satisfaction. I don't know how they will try to defeat the cult, but I am sure it's some way I haven't thought of, and I look forward to seeing what they come up with.