We know that standard chess has A LOT of possible moves, but I'm wondering how many possible moves are there in chess960? I mean you have many more starting positions (960) and, thus, many more outcomes. I don't think this has been asked before so I thought this would be the perfect time to ask it. : )

ADK

The number of legal chess960 positions should be only slightly greater than the number of chess positions. I'd say somewhere around 1.25 times as many, and most of the added ones are only there because of the different cstling rules.

One of the big advantages of playing 960chess, is that virtually every opening is unexplored.  So there is no advantages, per se, of having played a certain opening well, and knowing what someone will likely do!

If every one of the 960 different chess boards has 20 possible first moves for white and black (16 possibilities for the 8 pawns, and 2 possibilities for the 2 knights)...  That's 400 different combinations just for move 1 for white and black.

400 possible moves per board for move one...  so that's 384,000 different possibilities for move number one for white and black...  and that's just the first move!

So, it's practically impossible to have an "experience" advantage while playing...  But that's not to say that an experienced chess player can't do well, since all the same rules apply.  But it's highly unlikely that they'll have a special move to throw at you 10 moves in because they know what you're going to be doing as a result of studying openings.

It's fun!

Only 1.25x? I think 960 starting positions will rack upmore than that.

Yes. Most of the positions are reachable no matter what the starting position. The only positions that will be different are where the different castling makes a difference, and where there are a lot of pieces left on the first rank that there's no way they could have gotten to those positions due to the pawns being almost unmoved. The latter category should be well less than a trillion extra positions, which isn't even a blip on the radar. Therefore the biggest difference will be the great number of middlegame positions before castling where the king and/or rook of either player is in a different place and castling is still legal.