- "[...] Take the HP display, for example. If you get hit for five points, your HP goes down by five. The meter sort of spins, like a drum roll. You know those odometers in cars? The numbers spin and drop, “doo-doo-doo-doo”. Of course the numbers are displayed, but at the same time there’s this sensation we get from that visualization of a drum roll. I wanted to make it subconsciously entertaining. And I wanted to make a video game that didn’t just reek of–well, video games."
- — Shigesato Itoi
The rolling HP meter essentially prevents characters from dying until their HP has decreased to zero. This becomes more of a major strategic point as the party's maximum HP increases: A character can still use regular battle actions while they are taking damage, including repeated amounts of mortal damage. This also applies to when HP is increasing as well, so if a character uses a healing item, the healing can be interrupted by a sufficiently powerful enemy attack. Should any characters have taken mortal damage, if they are alive once the player's turn comes around, they can enter commands as fast as possible in order to prevent unconsciousness. Defending during a turn can slow the rolling meter, but the speed will return to normal in the next turn.
In EarthBound and Mother 3, unconsciousness is only induced if a character's HP meter is at 0 at the beginning of any action taken by the player or an enemy. This means that if the gauge reaches 0 just after the character is targeted for Lifeup, they will be saved; if the gauge reaches 0 just before then, they will fall unconscious first and the PSI will be wasted. If any character hits 0 HP during the command entry stage, the character will not die until commands are finished, but before anyone can perform an action (including running away).
The same rules for the HP meter apply to the PP meter, although it has very little effect on gameplay; the PP meter always reaches its appropriate value after any PSI/PK attacks have been used.
The Rolling Meter doesn't exist in EarthBound Beginnings, and instead players will die automatically when their HP reaches 0.
- http://yomuka.wordpress.com/2009/04/30/famitsu-06191992/ A translated interview with Shigesato Itoi, held by Weekly Famitsu on June 19, 1992