Rules/features that only one sport has

There are some rules that are specific to a single sport, because they only make sense in the context of that sport. For instance, the infield fly rule. No point in asking why soccer doesn’t have the infield fly rule.

On the other hand, there are certain rules or characteristics, usually a bit more high level, that seemingly could apply to multiple sports, but only one sport has.

For instance:
-The Power Play. Is there any sport other than hockey that has a play-temporarily-shorthanded rule? It seems like it could fit fine in soccer, or possibly basketball. There are a few details of the power play that are hockey-specific (no icing during a power play, power play ends on a goal) but it is an interesting way to punish infractions, and it also leads to some variety and tempo over the course of the game.

-Stoppage Time. Are there any other sports with a clock, but a slightly secret clock? One thing I do like about it is that the ref has the discretion to keep the game from ending in the middle of an offensive chance. This is built into American football, since the game doesn’t end during a play (right?).
What else?

For hockey, I was thinking of how players are substituted during play. All other sports I can think of substitute players during a stoppage in play.

Rugby, hand ball and field hockey have “power plays” where a person gets sent off the field for some amount of time.

Stopage time exists in soccer and I believe in Rugby as well.

Not quite a single sport, but so far as I know baseball and soccer are the only major sports where the size of the playing field isn’t set.

A bit odd… but sailing changes the course during the race. I can’t think of another sporting event that changes the course/size of the playing field during the actual competition.

In baseball, the defense controls the ball.

and cricket

and cricket

What do you mean? Like, while the race is actually in progress? People are deliberately changing the course? Or does it depend on markers that can move around based on winds/tide?

Indoor soccer has power plays.

The two minute warning is unusual in football. It’s an automatic timeout not assigned to either team, and there are rule changes within the final two minutes.

Baseball’s use of innings and continuing until there is a winner may be unique. I’m not sure how cricket works but I understood there was a fixed number of innings and the game can end in a draw.

As the boats are sailing towards one buoy the next buoy marking the course may be moved by the race committee, depending upon whether the wind direction changes. It is not merely the buoys drifting around, but rather race officials actively moving the course markers.

More of a feature than a rule, but SCA heavy combat doesn’t segregate its combatants based on gender or weight class.

How do they let the racers know that? How can it possibly be fair?

Does any sport but hockey have a penalty box?

Notification is dependent upon race rules. A flag on the race committee boat may be raised or a radio transmission made to the racing boats.

The new buoy location will be in a predictable direction in relation to the current wind direction when the first boat passes the preceding buoy. It’s just that the new buoy location may be in a very different physical location relevant to the prior location.

The theory is that it is fair since all racers since each complete the same course. It is just that as the boats are proceeding from buoy #4 to buoy #5 the race committee may note a wind shift (or change of wind strength) and move buoy #6 before the first boat reaches buoy #5.

Literally a penalty box? I think indoor soccer has one. Lacrosse sends players off, I don’t know if they have a “box” they make them stand in. Soccer sends playere off as well – but it’s permanent, not temporary.

And replying to Chronos, “Not quite a single sport, but so far as I know baseball and soccer are the only major sports where the size of the playing field isn’t set.”

Hockey rinks are different sizes. There is a standard (two actually), but the actual rinks vary.

Golf has no standard size for courses either. It’s not quite the same as a field of play though.

And auto racing doesn’t have standard tracks.

And hockey.

Is golf the only sport where low score wins?