Chess variant with most possible moves per turn

A typical chess position has about 30 possible moves on average compared to about 5 for checkers. Arimaa which can be played using a standard chess board and chess pieces has on average 17,000 possible moves from a typical position. Yet human players are not confounded by this vast array of options. Instead they feel much more creative in expressing their style of play and never have to worry about memorizing openings. Computers on the other hand hit a brick wall when they try to brute force the Arimaa game tree. Since 2004 the AI community has been trying to win the $10,000 Arimaa challenge prize by defeating the top human Arimaa players, but each year the humans have continued to prevail. The current Arimaa world champion also happens to be a high ranking poker player. Just google 'arimaa' to learn more about it.

One of the first things I learnt when I looked it up is, that, while being playable with a chess-set, it is not exactly a chess variant.

The way how pieces interact with eachother is completely different than in chess. In a unique and refreshing way that is.

I must admit I really enjoy it. (as you might imagine, when I did a search on threads about it and now post in them)

I found this interesting comparison with chess:

http://www.convinceme.net/debates/5991/Arimaa-vs-Chess.html

Looks like many people who know both actually like it even better!

Main disadvantage for me really is it's low degree of prominence. And that it kinda spoilt chess for me a little by brutally displaying its shortcomings.

Arimaa is not a Chess variant any more than Checkers or Go are Chess variants. No Royal piece, no replacement capture...

Of course the seemingly large number of moves is brought about by in fact making it agame where you can do multiple moves per turn. Marseillaise Chess, which is basically normal Chess where each player can do two moves per turn, does offer you choice between a thousand 'moves',  (actually move pairs), typically. There is a variant 'Progressive', where you do one move in the first turn, two in the second, three in the third, etc. From the third move on this already has more moves than Arimaa.

I agree that Arimaa is not a chess variant but a very different game you happen to be able playing with the same equipment.

Of course one can easily come up with other variants that have several steps within one move but making it a fun, balanced and overall well-designed game as Arimaa at the same time probably is the tougher part.

Especially if you play with unaltered chess-rules otherwise. I'd guess that would lead to checkmating very, very soon.

Indeed, Progressive Chess games never last many moves.

Don't know about Marseillaise Chess, though. I understood that it used to be seriously played, and even had its own leage of players. So I guess it must be a non-trivial game.

Ultima is another non-Chess-variant that can be played with Chess equipment, but where all piece move and capture completely differently. (Not excessively many moves per turn, though, although many more than Chess. Pawns move like Rook there, and all (non-royal) pieces as Queen.)

I forgot to mention 'Chieftain Chess' as another variant with a huge number of moves. Possibly even more than Arimaa.

In Chieftain Chess each side has 4 royal pieces (called Chieftains rather than Kings; they also move differently), and you can move as many pieces in one turn as you have Chieftains. (But the piece has to be within a certain distance of the Chieftain to be activated by it.) You lose when your last Chieftain is captured.

You cannot move the same piece twice in the same turn, but there are many pieces, and most of them are much more powerful than the '1-orthogonal-step' pieces of Arimaa. (The board is 16x12, and even your 16 'Pawns' all move like an orthodox King.)

I like the sound of this game.