TINY-HUGE ISLAND/WING MARIO OVER THE RAINBOW
Tiny-Huge Island seemed to be inspired by World 4 of Super Mario Bros. 3, in which the normal-sized level can be switched into an enlarged version and vice versa by traveling through specific areas or warp pipes. This world always represented the point of the game where my progress came to an abrupt end, and Tiny-Huge Island from Super Mario 64, while not quite as troublesome as its 2D predecessor, still has some major issues. In the painting room, you can actually choose which version of the level you want to start out in, although you always start the level in the same enclosed space behind a gravely wall. By jumping into a few set warp pipes throughout the level, you can change the level's size from minuscule to large. It doesn't matter too much, however, because the tiny version of the level mainly just serves as a means to get around faster and locate a couple of secrets. Almost all of Tiny-Huge Island's power stars must be obtained on the large portion, and they are pretty aggravating to collect, from battling it out against several gigantic Piranha Plants on a steep plateau to racing against the fleeting Koopa the Quick. The worst thing about Tiny-Huge Island, however, has to be the fire spewers. There are literally DOZENS of these things spread all over the island on both variations of the level, and being hit by one makes Mario run around uncontrollably while quickly losing a third of your life bar unless you can jump into a body of water fast. Since the level is situated above a bottomless pit, and there are several areas with precarious cliffs and gusts of wind, you REALLY don't want to lose control of Mario. Wiggler's cave is pretty bad, too, ESPECIALLY the 8 red coin mission where you have to make several cautious jumps over another looming abyss inside a cramped cave with little space to land on the platforms.
The real kicker of Mario 64, however, is Wing Mario Over the Rainbow, hands down. It's not a regular 6-star level like Rainbow Ride, oh no; it's a level solely dedicated to a red coin mission. And it takes place in the clouds above another steep drop. There is very little ground in the level since most of the flooring is comprised of floating clouds, so you have to use the stiff Wing Cap controls to fly between the platforms. Some of them can be really far up into the air, requiring either extreme flight skills or a well-aimed shot from the cannon on the pink platform near the bottom, and one has you grabbing onto a POLE (in the defense of this case, there are quite a few poles under the cloud, but it's still VERY easy to miss your mark and fly right past them). Worse still, not every platform contains a wing cap, so if your power-up runs out while you're on a faraway cloud you're pretty much screwed and have to commit suicide. Actually, no, you can't even do THAT, because falling into the void under the level, rather than killing you, dumps you INTO THE CASTLE MOAT. This means wasting another two or three minutes going back into the castle and trekking up the stairs just so you can try again. It's pretty silly how the hardest level in Super Mario 64 happens to be a side-stage, but it's brutal nonetheless, and if you're not going for a 100% completion run you're better off just skipping this one out.