Bomb Float · Food for Thought
The float is in the title for a reason. It is the single verb that separates Bomb Jack from every other 1984 platformer, and the one Bomb Float builds its whole feel around.
The hero of Bomb Float has almost nothing to work with, and that is the point. He can run left, run right, and press one jump key. Out of that jump key the engine coaxes five distinct behaviours, and learning to feel the boundary between them is most of what it means to get good at the game.3
Press jump from the ground and the hero gets a fixed upward kick, the engine sets his vertical velocity to −270 pixels per second (negative because up is negative on the screen).3 That is the first behaviour: the launch. The second is the variable height. If you release the key while the hero is still rising from a jump off the ground, the engine multiplies his upward velocity by 0.45, cutting the rest of the climb short. A mid-air lift is exempt: it is a fixed-height impulse, and letting go after one does not trim it.3 Tap for a hop; hold for a full leap. Every good platformer since Super Mario Bros. has some version of this, and Bomb Float’s is textbook.
The third behaviour is the one an arcade player reaches for by instinct. Tap the key again while the hero is already in the air and he gets a fresh kick upward, his vertical velocity set to −230 px/s against the −270 of a jump from the ground. That is worth about 33 pixels of climb to the ground jump’s 46, so a lift is a little under three-quarters of a jump. He has three of these taps per flight and they refill only when his feet touch something, so the hero can climb but he cannot simply fly: a ground jump plus three lifts buys roughly 144 pixels of height, and then he is out until he lands.3 This is the other verb the original arcade game leans on, and it is why the levels are stacked the way they are — the ledges above the first tier are simply out of reach of a single jump. The fourth and fifth behaviours are where it stops being textbook and starts being Bomb Float.
Once the hero is airborne and has stopped rising, holding the jump key does something the original arcade game is famous for: it slows his fall to a drift. The engine implements this with two gravities. Normal gravity pulls at 760 px/s². But the moment the hero is off the ground, holding jump, and no longer rising — from the apex onward — the engine flips him into a floating state and swaps in a float gravity of just 150 px/s², barely a fifth of the normal pull.3
It also caps the speed. A normal fall is limited to a terminal velocity of 360 px/s; a floating fall is capped at only 90 px/s, one-quarter as fast.3 So the difference between falling and floating is enormous: a fifth of the acceleration and a quarter of the top speed. Let go of the key and gravity snaps back to full: that is the fifth behaviour, the deliberate drop, and it is how you come down fast when you need to. Hold it instead and the hero hangs, drifting sideways at his ordinary run speed while barely sinking.
| Quantity | Falling | Floating |
|---|---|---|
| gravity (px/s²) | 760 | 150 |
| terminal fall (px/s) | 360 | 90 |
| jump velocity (px/s) | −270 | −270 |
| mid-air lift (px/s) | −230 | −230 |
| run speed (px/s) | 96 | 96 |
Those numbers are the whole game feel in a table. Because the horizontal run speed stays a constant 96 px/s whether you are grounded, jumping, or floating, a held float turns a jump into a long, flat, controllable glide. You are not solving a jump so much as steering a descent. In a play-field only 240 pixels tall, a fall capped at 90 px/s gives you the better part of three seconds to pick your landing, an eternity by arcade standards, and exactly the margin you need when the ledge you were aiming for has just been blown out from under you.3
A jump is a commitment. A float is a negotiation, you keep bargaining with gravity, one held button-press at a time, until you find a place to land.
Floaty platforming has a reputation, and not always a kind one, in a precision game it can feel imprecise, a hero who won’t come down when you want him to. But Bomb Jack understood in 1984, and Bomb Float re-discovers, that the float is perfect for a collection game played on a single fixed screen. When the goal is to touch every bomb rather than to survive a gauntlet of pixel-tight jumps, hang-time is a feature. It lets you re-aim mid-air, thread between patrolling enemies, and correct a route on the fly.1
The engine leans into that forgiveness in small ways elsewhere. The hero spawns with a stretch of invulnerability after every death, a full 1.5 seconds of it, so a respawn never drops you straight onto a waiting enemy.3 The whole simulation, meanwhile, runs on a fixed 60-hertz timestep, so the float behaves identically on every machine and a given seed always places the bombs the same way and lights their fuses in the same order (the shape of the screen itself comes from a hand-tuned set that cycles with the level).3 Forgiving movement, deterministic physics: the combination is what makes a floaty game feel fair rather than floppy.
Bomb Float is, at heart, a score-attack game, and it inherits that DNA directly from the arcade. Clearing the screen is never really in doubt for a competent player; the question the game actually asks is how many points did you extract while doing it? The scoring is built to reward discipline and punish carelessness.1
The engine of the score is the chain. Every lit bomb you grab is worth a flat 100 base points, but it also increments a chain counter, and each grab adds a further 100-times-the-chain bonus on top.3 The first bomb is therefore worth 200, the 100 base plus a 100 chain bonus; the twenty-fourth, if the chain has never broken, is worth 2,500. The chain is the reason a clean, unbroken run of all twenty-four bombs scores wildly better than a scrappy one, and the reason death hurts twice over, because dying resets the chain to zero.3 The engine even keeps your best chain of the run as a stat, quietly inviting you to beat it.
Lit bomb: 100 base, plus 100×chain bonus. Defeating an enemy while powered: 500. Clearing all 24 bombs: a 1000-point level bonus. And a rewarded “2× score” boost multiplies everything earned for the rest of the run.3 The optimal line isn’t just “clear the screen”, it’s “clear it without ever breaking the chain, and cash the power coin against a crowd.”
That power coin is the direct descendant of Bomb Jack’s bouncing “P.” In the original, Wikipedia’s Bomb Jack article records, filling the bonus meter summons “a circular bouncing ‘P’” that “will turn all the enemies into bonus coins for a short period.”1 Bomb Float keeps the fantasy and times it precisely: grabbing the coin gives the hero 6 seconds during which touching an enemy defeats it for 500 points instead of killing you.3 The score-maximising player doesn’t grab the coin the instant it’s safe; they save it for the moment the most enemies are clustered, and turn a panic into a payday.
None of this would exist without a small 1984 arcade game that a former cleaning-equipment company shipped under the name Tehkan. Wikipedia files Bomb Jack as “a 1984 platform game developed and published by Tehkan,” designed by Michitaka Tsuruta and Kazutoshi Ueda, starring a caped hero who “can perform high jumps and float in the air” with the goal “to collect all 24 red bombs on the screen.”1 Tehkan would not rename itself Tecmo until 1986, so the original marquee never actually read “Tecmo’s Bomb Jack”, a detail worth keeping straight.2
What made it stick was not the premise but the ordering hook. The bombs were not interchangeable dots. “Once one bomb is collected,” the record reads, “bombs will light up in sequence; if one lit bomb is collected, another will light up,” and collecting the lit one filled the bonus meter faster.1 That optional discipline, chase the lit fuse in order to score, or grab whatever’s nearest just to clear, is the seed of everything Bomb Float does with its chain. The homage simply hardens the suggestion into a law: here, only the lit bomb is live at all.
The original wrapped the loop in an arcade economy that Bomb Float mostly leaves behind. Bomb Jack layered on lettered pickups, a “B” that raised the score multiplier up to five times, an “E” for an extra life, a rare “S” that awarded a free game, and populated its “five different screens” with birds and mummies that could morph into flying saucers and orbs.1 Bomb Float keeps the two ideas with the most personality, the lit-fuse order and the enemy-eating coin, and quietly drops the coin-op paraphernalia that only made sense when the machine wanted your next quarter.
| Bomb Jack, 1984 | In this build |
|---|---|
| caped hero: high jump + float | kept, as core physics |
| 24 bombs on one screen | kept, exactly |
| lit-fuse bonus order | kept, hardened to a rule |
| bouncing “P” enemy-eater | kept, as the power coin |
| B / E / S bonus letters | dropped |
| morphing enemy types | simplified to orbs + birds |
| — | added: detonating bombs that deform the terrain |
It is a fair question why a design from 1984 still supports a new game at all, when so much of its era has aged into pure nostalgia. The answer is that Bomb Jack’s core is unusually abstract. It is not a game about a specific fiction or a specific enemy roster; it is a game about a floating body, a fixed set of targets, and an optional order that rewards the disciplined. Those are geometric ideas, not period ones, and geometry doesn’t date.3
Bomb Float’s bet is that you can take that timeless skeleton, render its float faithfully in modern deterministic physics, keep its score-attack soul, and then add exactly one new organ, bombs that reshape the level as you clear it, without the body rejecting it. On the evidence of the code, the bet pays off precisely because the float was already there to catch you. A game where the ground rearranges itself would be cruel if the hero fell like a stone. Give him a glide, a couple of seconds of hang-time, and a run speed that never changes, and the collapsing terrain becomes a puzzle you can actually solve in mid-air.3
The caped hero learned to float in 1984. Four decades later, the ground finally learned to move, and it’s the float that makes the moving ground playable.
That is the quiet thesis of the whole series. Bomb Float is not nostalgia for its own sake and not a remake. It is an argument that the best forty-year-old ideas are the ones abstract enough to still be built on, and a demonstration of what one careful new idea, laid on a floating hero and twenty-four bombs, can do.1