While not a difficult course in terms of level design (outside of a few tough jumps), World 8-1 does its best to unnerve you into playing sloppily by giving you entirely too little time in which to complete the stage at a reasonable pace.
Compared to some of the more recent World x-1s, 8-1 plays it pretty tame. The predominant enemies here are Koopa Troopas and Goombas, with a liberal sprinkling of Piranha Plants in the pipes and a handful of Buzzy Beetles and Koopa Paratroopas to deal with. If World 8-1 gave you, say, 400 ticks on the clock, it would be a breeze: You could play cautiously and ease your way through the whole thing without breaking a sweat.
But World 8-1 isn’t about going easy on you. It’s about breaking you over its knee. It’s about giving you a fraction of the ideal completion time to work with and forcing you to rush through the level. It’s about filling the stage with all kinds of nasty little setups that wouldn’t be much threat to someone navigating with caution, but which will definitely catch you off-guard as you sprint to beat the clock.
This level’s favorite trick is to break open the ground, dotting the landscape ahead of you with narrow pits. For the most part, these are single-block pits, which means you can run right over them. But these pits are often patrolled by inconveniently placed Koopas — either bounding Paratroopas that bounce into you as you run over the gaps, or else wandering Koopa Troopas that patrol the ground on the far side of the pits. These have a tendency to show up just as you relax slightly at having made it over the holes safely, creating an obstacle right where you least expect it and forcing you to be ready to follow up a sprint over broken ground with an immediate leap.
The presence of so many single-block gaps mixed with occasional larger ones requires deft mastery of Mario’s running abilities. Not just running, but knowing when to alternate modes — when to switch from a dash to a mere saunter, how to control the arc of Mario’s jump and his inertia, and more. Throughout the early stages of the game, Super Mario Bros. taught you how to make use of these techniques, and now you’re expected to synthesize and apply what you’ve learned.
If World 8-1 is the advanced class in level mechanics, 8-2 is the graduate course. Nearly every nasty trick the game knows shows up here.
The stage begins with a staircase and the appearance of Lakitu, similar to World 6-1, but with a twist: A Koopa Paratrooper bounces down the stairs toward you. Also, the stairs are broken up with by gaps. You’re forced to dodge Spiny eggs and a leaping turtle on uneven ground filled with holes into the void. This single-screen tableau alone is one of the deadliest situations in the entire game to date — and the stage is just beginning.
Beyond here, everything about this level remains maddeningly difficult, though it does offer a few saving graces. If you take out Lakitu at the beginning — which isn’t hard, since he does appear hovering above a tall staircase, after all — he never really reappears. And secondly, with caution and forethought, you can stay above much of the level’s danger by sticking to the raised platforms. World 8-2 is more generous with its clock than World 8-1 was, so you can afford to take your time.
The Bullet Bill pincer setups from World 7-2 fill much of this stage, though they manage to be even more devious than before. In addition to their crossfire layout, they’re often accompanied by launchers situated above them on low platforms, leaving you even less room to maneuver.
However, the centerpiece of this level is a single crushingly difficult jump. There are no hazards in that segment, no need to rush. An extremely wide gap — far too wide for Mario to jump without running — demands to be cleared. But it’s preceded by two smaller gaps, and you have only a single block to make the jump from. You can’t really dash over the gaps, because a pipe sprouts from the ground immediately before the gap, which means you have to make a small running leap onto a tiny foothold, then jump again immediately. If you can clear this hole, the rest of the level doesn’t seem so difficult by comparison. More easily said than done, though: Until writing the Anatomy of Mario series, this leap is as far as I’d ever made it in Super Mario Bros. It’s a jump that had thwarted me for 25 years.
Also, you’ll encounter a random assortment of Buzzy Beetles hanging out in the spaces between pipes. They’re a footnote, though, and are more or less just there to annoy you.