Hey,
I’m one of the developers on the MakeCode team. We aim at Arcade having a relatively low bar with a high ceiling – most (if not all) of the tutorials on the homepage are intended to be able to serve as an entry point for new users of all ages, so they tend to be very explicit and and thorough for that.
For some more ‘aged up’ experiences, there are a few places I’d suggest you to start looking:
- Every once in a while we’ll host ‘gamejams’ where users will create games around a given theme with a time constraint (e.g. one to two weeks). Here are a few of our previous ones for reference: https://arcade.makecode.com/gamejam/all - there were a good number of entries across the board
- Here on the forum – we get a lot posts so it’s hard to think of which to bring up right away, but here are a few things that come to mind right away
- The user created 3d raycasting extension Raycasting 3D render -- Blocks Edition which has been in vogue lately – anyone can make their own extension which adds blocks to the toolbox to expand options available to users, which can be a nice way to have students work together (e.g. have one student with prior coding experience create an extension that adds a feature that the other students in the group can use in their game)
- another user made a gallery which shows forum games in an easier to pick out fashion, so I’d suggest perusing the ‘most liked’ games from the forums: https://games-gallery.jacobcarpenter.com/all-time
- We run twitch streams with some combination of me and the other devs on the stream (most) monday/wednesday/fridays over on https://twitch.tv/msmakecode . They also get mirrored over to https://www.youtube.com/c/MicrosoftMakeCode . They typically don’t get that polished as we try to stop ourselves from dragging on a single game too long as it can get hard for users to follow along, so they tend to be more concept or mechanic based, but there are good examples in there (and the entire games we end up with only really get worked on much in those ~1-3 hour groups typically). For one that I particularly liked, we hacked together loop hero - esque game in a few streams back around when that came out: Arcade Advanced Stream #307 - Loop Dungeon Pt. 3 - I’ll note we tend to make these games off the cuff so we don’t always come up with the ‘best’ way to do things, but I think that’s probably a benefit as an example for there being a somewhat high ceiling :).
I’ll tag in @KIKIvsIT for links to appropriately aged tutorials / skillmaps for this case 
. Probably worth a note here that if you don’t find the exact user generated tutorials similar to how we support user generated extensions (https://makecode.com/writing-docs/tutorials), but that would end up requiring significantly more work on your end so it’s not ideal.