To a casual observer like myself, the closest analogy i can give this game is Mutant League haha, this is a good thing as I love Mutant League! This helps Slaughterball stand apart from the other sports based games on the market as it has a unique setting and can build its own fluff and lore, and wont borrow from existing stereotypes.
The game mechanics seem simple enough; easy to learn but difficult to master... just the way we like them. Team rosters are made up of 4 types of players:
Butchers - Big smashy players!
Razors - Glamorous 4 armed scorers
Cleavers - Smart utility players
Slashers - Devious assassin types
Each team comprises an equal number of positional players to maintain balance and parity, and rather uniquely they are mounted on different shaped bases so they will stand out from other friendlies if you are playing straight out of the box unpainted (Shame on you!)
Erik, the Lead Designer of Slaughterball has posted up a quickstart version of the rules for public review. At 33 pages its not a complete work, but enough for you to get a feel for the game and try out some of the plays.
Have a good browse of the kickstarter page and pledge on!!!!