Funny, I just tried playing Mega Man X6 for the first time a couple weeks ago.
I'm sorry, but that game is fucking terrible. I've beat a TON of Mega Man games over the years, even some of the other really terrible ones, like 7, 8, X5, MM&B, and uh... the entire MMZ series... and I just couldn't continue X6.
The first bad stage I came across was Ground Scaravich, which is pretty much the laziest designed MM stage ever (well, some of the MMZ stages might be a bit lazier), but then there's that part where it can spawn you into a random room that has a portal to go fight a side-boss, and is ridiculously hard to actually AVOID the portal so that you can continue the main stage and beat the boss. And then once you accidentally touch the portal, you're locked into that room and even if you die, you can't go back to the main stage, and then there's a boss that can spawn in there that I think can only be hurt by certain weapons, because nothing I had could hurt him.
But hey, I thought, it can't POSSIBLY be worse than that, right?
Nope. Blaze Heatnix's stage proved me wrong. A marathon against a single midboss that you have to fight like 5 or 6 times in increasingly annoying rooms. And that's it. There's nothing else to the stage. So I figured I had managed to complete the worst Mega Man stage ever.
And I was probably right. That WAS the worst MM stage ever. But I wasn't yet done with the game... Because I eventually got to Metal Shark Player's stage (who the fuck comes up with these names!?)...
The stage in itself isn't really THAT terrible. It's just that there's ONE fucking jump at one part of the stage where you're stuck between a crushing ceiling and spikes all around that I just couldn't get past. I died over and over on this one jump. So I figured I must have been doing something wrong and looked it up on Youtube. Turns out that you pretty much have to have the hover boots to cross it, but even then its a series of pixel perfect jumps + hovering in order to get across that ONE fucking pit.
So yeah, that game is just BAD. I can't imagine what sort of horrors may have come after the stages I had already beat...
Honorable mention to uh... I can't remember what stage it was, but there's a secret room that you can just walk into, with no extra parts or abilities necessary, which holds an item on the far side of a long pit of spikes. You need a leg attachment of some kind to cross it, so if you don't have it, you'll die every time... only to respawn in that very same room every single time with no way to escape but to fling yourself into the spikes until you get a game over...
So yeah, fuck X6.