It's an interesting question and debate about exactly what "world under glass" means. I'd say it is definitely subjective and everyone is going to have a slightly different definition. I guess for me, it is about how much the physical aspects of the game pull me into the theme.

Immersion is a factor, but not the only part of it. For example I find Star Wars to be very immersive, and it feels like I am a part of the films when I am playing. However, that is all because of the code and brilliant use of the audio / video assets. There really isn't much physical which pulls me into the world if you stripped the code away.

Spider-Man on the other hand...that I would call a world under glass. I am physically fighting the villains, each in a slightly different way, even without the code. The software enhances it, but doesn't create it, if that makes sense. Plus things like the shape of the ramps and overall flow of the shots make it feel like you really are Spidey swinging through NYC. Iron Man is very similar in this regard, even with how "stripped down" the playfield is. There is no question that you are physically fighting those bad guys.

I love the Haunted House answer above by Honch. That is a perfect example. The "code" from that era is simple, and really has nothing to do with the theme (other than music/sound of course). But the playfield quite literally IS a Haunted House, complete with multiple floors, hidden passageways, trap doors, etc. This is a perfect example of "world under glass".

I may get some flack for this one, but I'd call Avengers a pretty good example as well. You have Hulk which you physically fight and he not only fights back, but also wreaks havoc by actually "destroying" the bridge/ramp. Plus spinning the Tesseract, and Loki physically locking the orbs bring a lot of the world together. Sure, the art could have really helped build a better world, but I think it's a decent example.

X-Men is another that brings the world to life physically, especially with Magneto's magnet usage, Ice Man creating an ice path, and Nightcrawler popping up out of nowhere. Add the software which uses lighting to add a lot of immersion and mood to different modes (especially Storm!) and it definitely fits my definition.

I think Batman '66 and GoT are two that ALMOST get it right, but really need the software to bring it together. Batman with the turntable mech brings a lot of the world into a physical form. GoT has a freaking dragon which flaps it's wings and fights back (pro at least). The LE even does a pretty good job making the upper playfield into a castle. But I would say both of these games do not really transform into a "world" until you add in the software. Then Batman comes alive with the video/audio and GoT comes alive with things like the Winter is Coming lighting putting you smack into a blizzard.

America's Most Haunted is a good one with a ghost you actually battle, door to knock on/open, creepy elevator, etc. It brings the world to life on the playfield.

Jersey Jack seems to have a knack for it as well. WoZ, DI, and POTC all definitely bring their worlds to life physically on the playfield. I would also say most of JPOP and Lawlor games have at least some level of "world under glass" to them. Even Lawlor's less loved titles like RCT and CSI still bring their world to life physically.