BaCC stands for “Build a City Challenge.” You basically create several “founder” sims and work on building a neighborhood from scratch, usually following a rule set. I’ve seen several out there – one of the most popular is Nepheris’ rule set, but many other Simmers have adapted the rules to better suit their play style. For example, check out DeeDee’s and Mara’s rule sets, as well! I started my own neighborhood from scratch, but I kind of wish I did it as more of a BaCC – it seems more fun and challenging, and definitely paces the building a bit more! *guilty of building seven community lots before completing a single round of play*
ROS stands for “Random Occurrence Scenario.” You basically use a program (or I suppose you could manually roll die) to randomize different events for your game. Some of them are minor, such as making your Sims have a sleepover, while others might really shake up your game play, such as making a family member move out. D: I haven’t decided if I’m ready to commit to this level of randomness yet, but it’s definitely good for those who want a challenge! You kind find different ROS files here, here, and here. 😀