It’s probably happened to you: After bashing your head against a particularly difficult boss in a video game, you realize you’ve been duped. As you watch that boss’ depleted health bar fill up again, you realize what you thought was a victory was instead an insult. Welcome to phase two of the battle you believed you’ve just won.

These moments can be deflating and infuriating. But I’m here to defend them. As part of Polygon’s coverage of dramatic entrances in video games, movies, and television, allow me to sing the praises of the dramatic re-entrance, the moments that transform highs into lows.

The second (or third, fourth, etc.) health bar is a longstanding design trick in games, implemented for multiple reasons. Some instances of double health bars are more successful than others, but they serve important purposes: They reframe the boss fight experience, add new layers of challenge, and force players to (in many cases) try and try again, armed with fresh knowledge and skill.

Health bars (or meters) have been used in games for more than 40 years, building on the “hit points” system introduced in Dungeons & Dragons. Early arcade experiences like Nintendo’s boxing game Punch-Out!! and Konami’s fighting game Yie Ar Kung-Fu relied on health bars to show players how much stamina or life they had left. Health bars are commonplace across genres, from side-scrolling beat-’em-ups and shmups, to action RPGs and strategy games. Most health bars drain based on damage and replenish based on power-up items. Some, however, simply fill up based on game designers’ whims.

While many consider the refilling health bar a cheap tactic, I consider it a huge boon to game design. Let me explain why as we discuss the multiple ways health bars can be used for good and evil.

[Note: The following story may contain spoilers for boss battles in games like The Legend of Zelda: Tears of the Kingdom, 2004’s Spider-Man 2, Super Metroid, and a half-dozen FromSoftware games.]

In classic games like Capcom’s Final Fight, Sega’s Streets of Rage, and Treasure’s Ikaruga, some enemies break the rules with layered health bars that must be drained multiple times — technically refilling after being depleted.

More modern series like Bayonetta and Yakuza/Like A Dragon use the same tactic, piling on health for more challenging opponents. In Yakuza Kiwami, for example, a recurring Yakuza boss named Jo Amon has more than a dozen health bars that must be whittled down.

Why not just use one BIG health bar in these instances? Because the layered health bar communicates to the player that whomever you’re fighting is a Big Deal: Their capabilities are unknown, and you need to take this fight seriously. Creating a visibly longer health bar to convey the depth of your opponents hit point pool might break a game’s UI. Alternatively, if players were shown draining a smaller amount of health from a multilayered-health-bar boss, the game might confuse players into thinking their attacks had been diminished, or that they should pursue a different strategy.

Layered health bars are often implemented out of pure utility, to keep gameplay communication consistent and give players an extra challenge. Thus, they are one of the least compelling types of refillable health bars in games.

Here’s where things get more interesting. Rather than presenting players with health bars in bulk, like you were fistfighting at a Costco, some health bars in games will refill or stack as players enter the dreaded second phase of a boss battle.

Second-phase boss battles with refilled health bars were present in classic games like the original Castlevania for NES and ActRaiser for........

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