This will be a quick primer to bring everyone up to speed on what the heck I mean when I say I'm "playing fantasy football." If you have prior experience playing the game, then feel free to skip this one.
So, what exactly is fantasy football? There are a lot of variations and optional rules that different leagues follow, but the core mechanic is the same for all leagues. Over the course of an NFL season, individual players generate individual statistics. The players on offense produce two key ones: yards from scrimmage and touchdowns. Most leagues focus exclusively on these two stats(with a few notable exceptions, which I will get to), and our league follows suit, but any league can expand their stats to include things such as total touches(how many times does a player handle the ball?), total receptions(how many times does a player catch the ball?), and any other stat that is tracked by the league.
Each team owner puts together a list of players from the NFL, and we compare which group of players get the most yards and touchdowns. Each week, we create "starting lineups" from our lists and only points scored by starters count. This way, each team is equal numbers of players from the various positions in football. Our league's starting lineup is set up as:
WR/RB "Flex"(you can choose either a running back or a wide receiver for this slot)
Defenses are selected as full teams, since individual defensive players can have misleading stats, and the strength of a defense is largely based on its overall success rather than the success of an individual player. For example, Nnamdi Asomugha was widely considered to be the best cornerback in football for several years, but he was so good that he never got any interceptions or tackles, simply because no one ever threw the ball anywhere near him. Meanwhile, Asante Samuel racked up a ton of interceptions, but partly this was because he had a tendency to gamble, and found himself out of position and giving up a big play on several occasions.
To compare across different positions, we convert our stats into a single, simple metric called "fantasy points." Anyone who runs the ball or catches a pass gets 1 point per 10 yards gained. Anyone who runs or receives for a touchdown gets 6 points, just like in real football. Quarterbacks end up with higher stats just because of the nature of the position, so they score a little less - 1 point per 25 yards thrown, and 4 points for a touchdown. Players lose 2 points for the team for turnovers. Defenses get a point per sack, 2 points per takeaway, and either gain or lose a certain number of points, depending on how many real-life points are scored against them. Kickers get 1 point for a PAT(Point After Touchdown) but lose 2 if they miss a PAT. They gain 3 for a field goal of 0-39 yards in length, but lose 2 for a miss in that range. They score 4 points for a 40-49 yard field goal, but lose 1 for a miss. They also score 4 for a 50+ yard FG, but there is no penalty for a miss at that long range.
All of the starters' point totals are added up, and then compared to whichever team you play against that week - it is a head-to-head scoring system, so each team generates wins and losses by playing against a single opponent each week.
To pick the team, we do a "snake draft" - we randomly assign an order of picks from 1 to 10, and then reverse the order each round. At the end of the draft, which is 16 rounds, each team will have enough players for a starting lineup, plus 7 players on the "bench" that they can put into their starting lineup if they ever feel that it is more likely for them to score points than their current starters.
To improve our teams over the course of the season, we can turn to the "waiver wire" - the list of all undrafted players. If a person on my team got injured, for example, I could exchange him for a waiver player. We can also trade with the other teams, giving up value at one position to improve at another.
In the end, it's all about value - we want to accumulate the players we think will score the absolute most fantasy points, while minimizing risk of poor performances. 13 weeks into the season, the top 6 teams in order of win/loss enter the playoffs, and we continue with a single elimination tournament through weeks 14-16(there is a bye week for the best two teams). After 16 weeks, the last team standing is our winner!