Nimbus leap

There is no jump button.

Touching a platform bounces you. All you control is where you are when you come back down — and the camera never, ever scrolls back.

NIMBUS LEAP is an endless vertical climber built as a real Game Boy Color cartridge. It runs on original hardware, on a Game Boy Advance, and on any emulator you like. It remembers your record between sessions, because the cartridge has a battery in it.

Five critters, five ways to fall

Every one of them can clear the widest gap the tower will ever make. What separates them is how they handle in the air and what the A button does.

• KERO, an electric frog. The baseline, and a bolt straight up that clears whatever is hovering over the next platform.
• PYRO, a fire chick. Low gravity, a soft bounce, and a glide you hold to fall at a fifth of the speed. Turns a missed landing into a slow drift back.
• NIBS, a ghost cat. Almost frictionless, so it never quite stops drifting, plus a dash across a third of the screen.
• GOLEM, a mossy rock. Heavy, sharp arcs, the highest bounce of anyone, and a slam that drops it at terminal speed straight through a fragile platform — on purpose, for once.

They unlock as your record climbs: 300 m, 800 m, 1500 m.

The tower fights back

Platforms are not all the same, and above a certain height most of them are not the friendly kind. Fragile ones throw you once and fall apart. Springs and single-use trampolines launch you into the ceiling of the screen. Ice takes your friction away for the whole next jump, not just the moment you touch it. Moving ones simply refuse to be where you left them.

Pick up coins, a spring shoe for one enormous bounce, a bubble that carries you for two seconds, and a shield that eats one hit.

Wasps, crystal bats, ember moths, cloud jellyfish and something with one eye patrol the gaps.

Five biomes

The tower changes every 250 metres and dissolves from one into the next without a single black frame: a leafy garden, a crystal cavern, a volcano, a sea of clouds, and an aurora void where the platforms are dark glass with a neon rim.

One more thing

The critter picker has five slots.

The fifth one just says ????, and no amount of climbing will ever open it — that is enforced in the code, not just unlikely. It is a sequence, entered on the title screen, and if you have owned a console at any point in the last forty years your thumbs already know it.

Get it right and something small and cloud-shaped wakes up. It can stop dead in mid-air.

Built properly

The tower is infinite, which means it is generated as you climb, which means it could very easily generate a jump nobody can make. That failure does not crash and does not look wrong in a screenshot — it just quietly ends your run at 1300 m after a good climb.

So it is proved instead of hoped for. Every jump in the tower is flown on a desktop computer before the cartridge ships, with the real physics code, with every critter, from the worst possible starting edge onto the narrowest legal landing — including runs that start drifting the wrong way. Seven million assertions, every build.

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Made by Eris Games.