That calls for a poll. I take the freedom to add some points to your list.
In the poll below don't assume that all attributes must fit to a single sport but instead might be matched by a set of sports. Best not to imagine a specific sports idea but rather what you require of proposals here.
Rationalist sports should...
have a low rate of accidents [pollid:707]
have cardiovascular benefits [pollid:708]
aid muscle development [pollid:709]
train muscle and motion control [pollid:710]
include social interaction [pollid:711]
help develop confidence [pollid:712]
include mental tasks [pollid:713]
be easy to learn [pollid:714]
be fun [pollid:715]
improve balance [pollid:716]
train reflexes [pollid:717]
useful for self-defense [pollid:718]
train spatial navigation [pollid:719]
use multi tasking [pollid:720]
be pleasant for spectators [pollid:721]
contain pauses [pollid:722]
have a duration of X minutes [pollid:723]
And for the sceptics:
The whole idea of a physical rationalist sport is bullshit [pollid:724]
The whole idea of a mental rationalist sport is bullshit [pollid:725]
Maybe we're trying to solve too many problems at the same time. In analogy with Purchase Fuzzies and Utilons Separately, I'd guess that the activity that best promotes physical fitness isn't the activity that best trains transferable skills isn't the activity that is the most fun, so spending some time on something intended to improve physical fitness, some time on something intended to train transferable skills and some time on something intended to be fun is probably better than spending a lot of time on something that haphazardly tries to achieve all th...
This post is a bit of an experiment; Most of the time, Discussion post lay out an idea and this idea then get commented upon. This post, on the other hand, will be purely about discussion on a topic. If this works out well, I'll might post more of these in the future.
On to the meat of this post:
I got this idea from a reddit post on /r/LessWrong.
To quote:
So have at it.
I only ask for one thing and that is to hold off on proposing solutions for 24 hours before giving suggestions for actual sports. In the first 24 hours, please discuss what makes current sports unappealing to rationalists and what aspects a sports designed for aspiring rationalists should have.
Edit: The 24-hour window has closed and solutions and suggestions can now be given.