Let us discuss of the Plaftorm Builder iceberg. This picture is WIP of course, so feel free to comment any other possible entries. (plus I've attached the original .pdn file so you can make your own)

Explanations about why x entry is at y tier
Spoiler [Everyone knows that]
Mario Builder: More well-known that PB itself.
Example file: Everyone tried it at least 1 time.
Setap is a smg4 fan: After all he's super famous outside of PB. (he's a legend on smg4amino)
Plugger Zone: Very well-known and the best discord yet.
Female gruppy: Yes.
Alpha 1.0: Very famous version since cmon everyone already checked the oldest versions for fun uh?
Stickman Bad luck: Very well-known too.
[Pretty well-known]
-Mechasaur hates level mayhem: Everyone who didnt seen the Level Mayhem meme is
-Back+lclick: The opposite of obvious but we can learn about it pretty ez.
-Seggaw: RIP
-Pre 5.3 hud: Seen on thousands of old screenshots and footage including the Alpha 1.0.
-The Tapatalk forums: There's literally a "Old forums" link on the forum summary.
-The UPE: Very well-known too.
-Gun Banzai: Most people already heard about CSB Antikore edition, however not much actually know the pre-CGM name. Shoutouts to the PB wiki btw
-AE's introduction thread: 6.4k views for 92 replies when i'm writing this, the only most popular threads are the PB memes thread and the 5th major games (ASM, Invasion, Castle Chamber, Level Mayhem and Matt's Adventure).
-Mario Bros 5: Is a awesame game
-CGM is a Sonic fan: He never mentioned it until rencently as I know.
-Ghwast private beta: Private beta for Aidanete friends
[Not very known]
-Mario Builder leftovers: Not much ppl played Mario Builder AND PB. (or...?)
-TingTHing is a drummer: Drum cover virgo is the best munsic
-The Obamium game: The peak of comedy.
-TIngThing 2nd channel: Never mentioned since the official thread talking of this.
-Gizgrod channel: Lets be honest...
-PB3: Never happened as I know.
-Mechasaur's PB Discord: Eh, people probably seen the 1st Discord thread !
-Incorrect designs on the 5K celebration thread: Setap was based on his first avatar, Alley had same design as Invasion's hero, Antikore and CGM's designs looked nothing like their canon design since I based myself on their old pfps, Mechasaur was based on the purple hair waifu pfp, TingThing's design was badly redone, and mine is yellow roblox guy (check the thread yourself)
-Warrior leaked the closed 8.0 beta day 1: Yes.
[Pretty obscure]
-Every enemy name: Even I don't know all of them (there's some enemies that don't appear in the enemy sprite selection and thus I can't know their names)
-Mad Brad: давайте будем честными 2 минуты никто никогда не замечал этот также его всегда была bad concept так что его довольно хорошие новости что Antikore отметил его для других игр.
-CGM sandbox levels: pretty obscure id say since CGM is mostly known for ASM and remasters/revamps of other people projects (CSB, cancelled Epic Platforms remaster).
-Early ASM had enemy capture: Mentioned in the ASM thread on the "out-of-date" section.
-Mr.Block: Anyone actually know this one?
-Project TC: Hey aidanete can you send me the pbx so I fix the intro softlock
-Matt's Adventure original purpose: Originally a fan replacement of the example file, idea was abandoned for obvious reasons.
-Warrior ripped off Invasion's hero: Forgive me Alley
[Really Obscure]
-The link between ASM and Stickman's Bad Luck: Only CGM (and maybe TingThing) knows.
-Warrior's defunct PB discord: Really obscure stuff since it was deleted.
-Setap's PB amino: Haven't been able to find it, was probably deleted due to inactivity.
-PB Player: Apparently around 2018 there was a thing that allowed to play PB games without explore. I have no information about this, so If you have some, please reply on this thread, I want to know.
-Matt's Adventure scenario: Only I knows and unlike "chitian gam maekr" I won't make it public until uh it's out
-Warrior's and mechasaur pfp list: I don't even know all my avatars, probably same thing for Mechasaur.