Basically, instead of once a player is drafted they are off the board like regular fantasy leagues, you are a GM with a salary cap. The players all are assigned a salary and you have to pick 1 qb, 2 rb, 3 wr, 1 te, 1 kicker and one defense. You have to stay under the overall cap, so you have to know matchups, etc to get the best bang for your buck. They also offer real time status updates on players, injuries, their performance against the team in the next game, and each player has an average Fantasy value assigned. You win buy placing in order of the total points your team accumulates.
Pretty sweet, a little difficult to win in the lower priced leagues which start at a dollar, due to the high number of entries, but if you can have a good week or few, you can literally win thousands. I won 800 last BBall season in a 1 dollar league..
A lot more fun than regular fantasy, because you can win money each week, and basketball season is great because you literally have games every night you can win from...