I discovered a glitch
after filling the star t room with water, you can go right again
it sends you to a blank room, but if you wait, the room will turn into the "just one mistake" room
but if you go back left before fixing the room, you'll enter a blank orange room, if you wait here instead of waiting in the other room, a brick platform will appear at the bottom, you can't see what happens if you go left before the brick platform appears, because there's just not enough time to get to the other side before it fixes itself
if you go left you'll enter a blank red room, if you keep going left and reach the middle of the room, it will be revealed that you are in the "it is always bats" room, and that you're standing on the text box at the top of the room, even though you are on the bottom (this room has the mechanic that if you fall to the bottom it sends you to the top, but the text box stops you from going to the top), you can jump from the text box to the other side of the room, but you won't be able to grab the letter (the jump is pretty big, I failed it multiple times)
but once you reach the other side you get to a room with a ladder, going down the ladder sends you to the other side of the TECH barrier, which I'd assume you're not supposed to have gotten past yet
but if you keep going left, past the ladder, you will go through multiple rooms of different colors, until you reach a room that has the H, but you can't reach it, because it's under a platform that you can't get under without falling into the room below, which is in-bounds (if you try to go back to the right in the H room, you just can't, the right side becomes a wall)
this confuses me though, because I thought I saw the H somewhere else in a video, or maybe someone else commented about it (now that I think of it, they might've been talking about this same glitch)
-- unrelated to the glitch, can skip until I say "back to the glitch"
another confusion is that in all the videos I've seen, they give the letters to the wizard guy and the game ends, but you can get past the wizard guy and over to the other side of the room, and it takes you to the "Jimi can swim" room, the same room as the "you were not supposed to be here yet" room, which leads to other water rooms, and eventually get you to the room that you fall back into if you fall from the H room (on the path you can also find the letter U)
also, there's an A letter block stopping you from getting past the "Jimi can swim" room, because it's below you, and you can't shoot downwards (shooting a wall and having your projectile FALL doesn't work for it), but you can shoot at the corner right next to the A block, and you'll be able to break it (this only works if you shoot upwards, not left)
-- back to the glitch
back to the H room, if you get to the top of all the platforms, you can go up into a room that just says "Hi." with blocks, this room seemingly has no other purpose
and that's about all I found
I uploaded a video of me performing this glitch to Outplayed's site (Outplayed is a free video recording program that is made for recording games with an easy keyboard shortcut, but they also have a screen recorder that you can use for anything, would recommend), and here's the link: