Rainbow Islands: The Bubble Bobble Sequel That Went Vertical

Taito released Rainbow Islands into arcades in 1987, two years after Bubble Bobble had made stars of two bubble-blowing dinosaurs called Bub and Bob, and the sequel takes almost nothing from its predecessor’s actual mechanics. Bubble Bobble was a horizontal maze game: trap enemies in bubbles, pop them, clear the screen, move to the next single-screen layout. Rainbow Islands throws that structure away entirely and replaces it with a vertical climb, one island stacked on top of another, a rising tide chasing the player upward from below, and a completely different core tool — rainbows, fired as solid platforms that can be climbed, thrown as weapons, or dropped on enemies from above. It is, structurally, a different genre wearing a sequel’s name, and the fact that it works as well as it does is down to how completely Taito rebuilt the moment-to-moment tension around a single new verb.

The rainbow as the whole design

The rainbow bridge is the mechanic the entire game hangs from, and it does three separate jobs simultaneously. Fire one horizontally into open air and it becomes a solid platform you can climb, letting you build your own route up a level that would otherwise be an unclimbable vertical shaft. Fire one at an enemy and it becomes a projectile, sweeping them off the screen on contact. Land a rainbow on top of an enemy from above and it becomes a falling hazard, crushing anything caught underneath as it drops back down. That’s a single input covering traversal, offence and a third option that rewards vertical positioning specifically, and the game’s level design is built entirely around forcing you to choose between those three jobs under time pressure, because the tide rising from below the screen never stops and never waits for you to finish deciding.

That tide is the mechanical genius of the redesign. Bubble Bobble’s screens had no clock — you could sit in a maze and work out a bubble-trapping route at your own pace, within reason. Rainbow Islands removes that patience entirely: fall behind the rising water and it’s an instant kill, no negotiation. So every rainbow you fire is doing double duty as both the tool for solving the platforming puzzle above you and the tool for outrunning the hazard below you, and the tension between “build carefully” and “build fast enough” is what the whole climb is testing, over and over, island after island. It’s a much more aggressive design than its predecessor’s unhurried maze-clearing, and it’s aggressive specifically because a single new mechanic let Taito attach genuine urgency to vertical movement in a way a horizontal maze never could.

Fruit, secrets, and the game underneath the game

Beneath the platforming sits a scoring layer that rewards a completely different kind of attention: collecting fruit and gems scattered through each level, many hidden behind requirements that aren’t announced anywhere on screen — certain enemies have to be defeated with rainbows rather than avoided, certain collectibles only appear if an earlier one was picked up within a time limit, certain routes only reveal bonus items if you deviate from the fastest path to the top. None of this is explained. It’s a game that assumes repeat play, arcade-style, where a first attempt is about surviving the climb and later attempts are about learning which islands are hiding a diamond behind a specific, unstated condition. That layering rewards the exact audience an arcade cabinet was designed to create — regulars who’d fed it enough coins to have worked out its secrets and could show a first-timer where to stand.

Taito buried enough of these conditions that arcade regulars spent months trading half-verified theories about which items required which specific action, in the era before a walkthrough was a search away — a genuinely social kind of discovery that a solved-instantly modern game rarely gets to produce anymore. Some of those theories turned out to be superstition rather than fact, a specific hazard of design this opaque: players will find a pattern in genuinely random behaviour if the actual rule stays hidden long enough, and separating a real hidden requirement from an invented one required the kind of communal testing an arcade’s regular crowd was uniquely positioned to do.

The visual redesign matters here too. Where Bubble Bobble’s caverns were uniform and cave-like, Rainbow Islands gives each of its seven islands a distinct palette and theme — ice, fire, a haunted-looking dark island, a candy-coloured one near the end — and that variety isn’t just decoration, it’s doing the job of telling a returning player roughly how far through the climb they’ve got without any on-screen counter. A player who knows the game can glance at an island’s colour scheme and know immediately what’s coming, which is exactly the kind of legibility an arcade cabinet needs when a session might last four minutes or forty depending on how well the last credit went.

Two players, one rising tide

Rainbow Islands supports simultaneous two-player co-op, and the design handles the second player with more care than the “just add a second colour sprite” approach a lot of contemporary arcade games settled for. Both players share the same rising tide and the same island, but each fires their own rainbows independently, which means a competent pair can build overlapping bridges, clear enemies from two directions at once, and — just as often — collide with each other’s half-finished platforms at the worst possible moment. That friction is deliberate rather than an oversight: a rainbow is solid to both players once it’s placed, so a badly timed bridge from one player can trap the other against a wall as the water rises, and readable Taito arcade design of the period generally treated that kind of shared-consequence chaos as a feature that kept two-player sessions lively rather than a bug worth patching out. It’s a rougher, less considerate co-op model than modern games would ship, and it’s also more memorable for exactly that roughness — arguing with a friend over whose fault a shared death was is its own kind of appeal.

The difficulty curve across a two-player run behaves differently to a solo one, too. Enemies scale in number to compensate for two characters clearing them faster, which means a pair who aren’t coordinating their rainbow placement can actually find later islands harder than a skilled solo player would, a genuinely uncommon design decision for the period that mostly treated a second player as pure advantage. Rainbow Islands treats a second player as a variable that has to be balanced around, not just accommodated.

Where the climb actually descended from

It’s worth being honest about what Rainbow Islands is really testing, because “vertical platformer with a rising hazard” is a structure that shows up constantly in games history without a straight lineage connecting them — the format keeps getting rediscovered rather than copied wholesale. What Rainbow Islands specifically contributed was making the climbing tool and the offensive tool the same object, so that every decision about where to place a rainbow was simultaneously a decision about survival, scoring and combat. Compare that to the beat-’em-up genre Renegade and Double Dragon were establishing in the same period, where movement and combat were separate systems layered together rather than fused into one tool doing three jobs — Rainbow Islands took a different route to the same era’s core problem of giving arcade players enough to master that a cabinet earned its keep on repeat coin-drops.

The arcade-to-home conversion problem hit Rainbow Islands particularly hard, because so much of its identity depends on smooth, responsive rainbow placement against a genuinely urgent rising tide — exactly the kind of fine-grained timing that dedicated arcade hardware handled easily and an 8-bit home micro, running the same logic on a fraction of the processing budget, often couldn’t reproduce without the whole feel curdling.

Spoilers below

The climb through all seven islands ends with a boss fight against Bubby’s nemesis from the first game reappearing in a final form, and the path there deliberately escalates the tide speed on the later islands well past what earlier stages trained you to expect, which catches most first-time players who’d built confidence on the opening few climbs. The seventh island’s colour palette shifts to something markedly darker than everything preceding it, and the game telegraphs the difficulty spike visually before it arrives mechanically — a smart piece of pacing that most genre imitators skipped entirely.

The hidden-fruit layer resolves into full “true ending” content for players who track every conditional bonus item across all seven islands without dying — a genuinely obscure reward structure that most players, arcade or home, never saw without a strategy guide, since the conditions triggering some of the rarer items are never hinted at anywhere in play.

The verdict on Rainbow Islands, decades on, is that it remains a better test of moment-to-moment decision-making under pressure than its more famous predecessor, precisely because fusing three jobs into one rainbow-shaped tool forces harder choices more often than a maze ever could. The climb asks a genuinely different question of a player than the original game’s patient bubble-trapping did, and that willingness to abandon a hit’s proven formula rather than simply reskin it is rarer in sequels of any era than it should be. Home conversions across 8-bit and 16-bit micros alike struggled to keep the rainbow physics feeling as immediate as the arcade board managed, which is worth knowing before hunting down a period-accurate home version rather than a modern compilation re-release — the compilations, running the original arcade code rather than a reduced home port, are the more faithful way to feel what the tide was actually built to do.

If you haven’t played the original, Bubble Bobble’s own C64 conversion is the right place to see where the cast came from before the sequel changed everything about what they were doing.