G: I’m going to trace the game’s stage structure, then compare walkthroughs with player recollections to identify the most likely wall and whether it was opaque, buggy, or simply brutal.

G: [Non-text content: thoughts; content_type=thoughts]

G: [Non-text content: reasoning_recap; content_type=reasoning_recap]

G:

The likeliest answer: Stage 5-1, the Violators’ jungle/cliff level

Your memory of “one specific bottleneck that either stopped me or marked the beginning of an obnoxiously hard second half” matches Stage 5-1 remarkably well.

The critical section comes after the jungle and dock areas, when you enter a cave and emerge onto a cliffside. Parts of the ground collapse only after you approach them. You have to:

1. Move forward slowly enough to trigger a hidden collapse.
2. Stop before falling into it.
3. Back up to build skating momentum.
4. Jump the newly exposed gap.
5. Stop again before rolling into the next concealed gap.

There are several of these in succession, followed by logs, narrow surfaces, ramps, fish, moving rafts, and water that kills you instantly. citeturn223711view1turn223711view2

One player documenting a complete NES-library playthrough independently identified exactly this spot as the place where the game stopped him:

He reached Stage 5-1 on his first serious attempt, repeatedly failed at the collapsing cliff section, and finally shut the game off for the night. He described the combination of concealed holes, required backing-up, and slippery controls as “pretty evil.” citeturn109108view3

That is unusually strong corroboration for your memory.

You probably were not missing a secret

I found no evidence of:

• a required item or special character;
• a hidden command;
• a defective cartridge condition;
• an undocumented route necessary to continue;
• a boss that could only be damaged by some obscure move;
• or a genuine game-breaking bug.

The problem was the interaction between three deliberately chosen mechanics:

Skating momentum. You cannot instantly stop, reverse, or make a clean standing jump. The character must accelerate, and existing momentum continues affecting lateral movement. citeturn109108view1turn109108view5

Instant-death terrain. Falling into water, spikes, pits, or even getting too close to some platform edges costs a life rather than merely draining health. citeturn109108view1turn223711view2

Trial-and-error hazards. Some dangerous terrain is not visibly distinguishable until it activates. Thus the game can require you to know where to brake before the game has shown you that braking is necessary. That is not a puzzle you could reason through on the first attempt; it is memorization purchased with lives. citeturn109108view3turn223711view2

So there was information you lacked, but it was not some external secret. The “outside information” would simply have been a map or walkthrough telling you where the invisible collapses occur and exactly how the game expects you to manipulate momentum.

The other plausible bottlenecks

Stage 3: the sewer platforms

This is the first serious warning that the platforming will become nasty. You must jump repeatedly between small platforms while water pours from pipes, then negotiate sloped ramps, fire jets, sewage, and narrow landing areas. Even the walkthrough simply calls the first sequence “hard.” citeturn223711view0turn223711view1

This could be your remembered spot if you recall sewers, pipes, flames, or landing on tiny platforms. But it is more of an early spike than the start of the final brutal stretch.

Stage 4: the second freeway and barrel truck

This stage has repeated thin platforms and then a survival “boss” where a truck throws barrels behind it. You cannot defeat the truck; you merely dodge the barrels until it eventually leaves. The game does not communicate that especially clearly, and one modern review describes the barrels as filling most of the screen with very little dodging room. citeturn223711view1turn109108view2

This is the best candidate for “I suspected I was missing something,” because a child might naturally assume there was a way to attack the truck. There isn’t. The actual requirement is simply survive an arbitrary duration. The helicopter at the end of Stage 2 works the same way. citeturn109108view1turn223711view0

Stage 6: conveyors over spikes

The final stage is an outright compilation of abuse: a timed maze, conveyor belts suspended over instant-death spikes, small platforms requiring immediate chained jumps of different lengths, wall-mounted fire, spike balls, barrels, and holes. The walkthrough notes that you can die merely by being near the edge of some platforms, suggesting especially unforgiving collision detection. citeturn223711view2

That is unquestionably Nintendo-hard, but if you reached it, you had already cleared the most commonly identified wall in Stage 5.

Was it practice, cheapness, or broken?

All practice, but practice forced by cheap design. Not literally broken.

There is genuine technique involved. Skilled players learn to countersteer, reverse briefly to shed momentum, approach hidden hazards slowly, and chain jumps immediately upon landing. The game supplies infinite continues and checkpoints between sublevels, which makes eventual mastery possible. citeturn109108view3

But contemporary retrospective opinions repeatedly converge on the same structural defect: the skating physics can be enjoyable on broad racetrack-like courses, yet the later designers apply those same slippery controls to precision platforming, concealed gaps, narrow ledges, and instant-death pits. citeturn109108view1turn109108view2turn109108view5

My judgment would be:

• Stage 1–2: difficult but basically teaches the skating system.
• Stage 3–4: uneven, with some poorly communicated survival sequences.
• Stage 5-1: the major bottleneck and most likely source of your memory.
• Rest of Stage 5 and Stage 6: the Nintendo-hard second half you suspected was waiting behind it.

So your childhood conclusion was essentially correct. You probably were not failing to understand an elegant solution. The game abruptly began demanding rehearsed precision from controls designed around momentum, while using concealed and instant-kill hazards to enforce that rehearsal. Beating it was possible, but it required memorizing the level until the unfair information disadvantage disappeared.

G: [Non-text content: reasoning_recap; content_type=reasoning_recap]

G: That sounds exactly like the kind of game that stays unresolved for decades—not because it was beloved, but because it was just interesting enough to make the unfinished business irritating.

An emulator is probably the right way to revisit it. Not necessarily to brute-force it with constant save-state crawling, but to remove the completely unreasonable tax of replaying twenty minutes of already-solved material every time you need three seconds of practice on one jump. You could save at the start of 5-1, play normally from there, and only make closer practice saves once you identify the actual bottleneck.

And if it turns out that 5-1 produces a sudden, visceral “oh, this fucking part” reaction, you will have your answer. If not, you can continue forward without having to recommit to the entire game each time. Either way, the uncertainty finally becomes cheap to resolve.