Decided to charge through Gotcha too. This one didn't take as long since it was already simplified pretty nicely, detail-wise, and I didn't have to offer any suggestions.
LOST09 - Gotcha!
-None of the secret areas are properly tagged, so nothing shows up in your secrets tally.
-All the teleporters in the map need red lighting.
-All the "open, wait, close" doors in the map--sectors 62, 80, 127, 128, 131, 132, 134 & 161--have incredibly long delays before they close again.
-The cyberdemon platform lowers like a lift, complete with a lift sound effect. Sector 30 has the same issue when it lowers. It should make a rumbling noise like stair building or a crushing ceiling. I think a floor lower action needs to be employed instead of platform generic change (but I'm just guessing. I don't have much knowledge of UDMF format).
-I wonder if the cyberdemon battle should be reverted to being more like it was in the original PC map. There's obviously not enough "RAM" for a spiderdemon, but what about barons? (And changing all the knights in the map into barons.) Because without some strong opponent(s) to distract/weaken the cyberdemon, this fight is much harder than it used to be, especially from a pistol start. Then again, maybe a tougher fight is a better idea?
-I don't know why sectors 176 & 177 exist, and they certainly shouldn't be tagged to lower like lifts.
-I wonder why the behavior of the "zig-zagging tunnels with lifts" area was changed. Lines 671, 670 & 669 are supposed to be walkover triggers that lower the corresponding lifts down the hall from them. Now you just press on the sides of the lifts to lower them, which is more predictable and not as unique as the PC map behavior.
-Regarding the above, walkover lines 668, 677 and 676 used to lower the sector 12, 1 & 8 lifts, respectively, so you could climb back down if you wanted to. This functionality is inexplicably missing.
-Sector 124 should probably be moved a few map units north so it's easier to jump down to sector 121.
-Line 208 should have its "monsters walk over" flag removed. I don't believe that vanilla had any monster-activated "door open stay" walkover triggers.
-Line 707 also needs its "monsters walk over" flag disabled, as there are no "walkover repeatable" monster-activated doors in vanilla.
-Sector 136's glowing light effect is broken.
-Line 61 should have a "door open stay" action applied to it.
-It's not exactly relevant anymore since you can just step up into sector 171 from sector 0, but I do think sector 141 should be extended so the player can make a clean leap into sector 171 without falling into the blood.
-The thing 17 soul sphere is kind of pointless, since the teleporter to the megasphere is right next to it. If possible, moving the soul sphere to a hidden location closer to the sector 65 area where it was in the PC map might be a better idea.
-The thing 43 megasphere has most of its flags disabled. It doesn't appear at all under most gameplay settings.
-I'm not sure if sector 116's glowing light effect is PSX-authentic. Can anyone verify? Or at least replace it with an effect we know PSX Doom could do?
-The teleport lines around sector 112 are missing their "repeatable action" flags. The teleport lines around sector 30 also need their "player can use back" flags disabled, as sometimes trying to step off the teleporter pad causes the player to use it instead.
-Lines 627 & 629 are not properly unpegged.