Despite all of the theming and speacial effects, Verbolten has never really felt immersive to me. It's fun and all, but I always felt like I was in a building, not hurdling through the forest. I think I have finally put my finger on why this is:
1. The most obvious is that you clearly turn straight into a (very ugly) show building with little theming on the exterior
2. The sets are too light. You go from pitch black to glowing bright green trees. I love the unique art style Verbolten has, but it draws attention to all of the empty space in the show building. You are never emersed on all sides and while it looks pretty, you never feel like the woods are all around you. There are two fixes to this problem: one, use darker colors for the sets, or two, use a headlight effect. Rock n Rollercoaster is a lot like Verbolten in the way it has bright colored set pieces surrounded by pitch darkness. Rock n Rollercoaster succeeds in feeling immersive because the effects don't light up until you get to them, as if being illuminated by the car's headlights. If Verbolten added in this relatively simple effect I think it would make the ride a thousand times better.
2. In my opinion, the design of the track is very important to the theming of the ride. As in most indoor coasters, Verbolten has you racing around the building in circles. This doesn't make it feel like you are twisting and turning through the forest at all. I hate to compare Verbolten to Rock n Rollercoaster again, but it's a good example of how I think an indoor coaster should be. In rock n Rollercoaster they solve this problem by tilting the sets at different angles. This gives you the illusion that you are twisting and turning through the city. Something like this would really help Verbolten.
3. It's too pretty. Don't get me wrong, I love how beautiful Verbolten's sets are, but it feels like anything but a haunted forest. Verbolten's designers decided against moving parts, which I respect, but brightly painted set pieces do nothing to make you feel like you're in danger and the wolves theme is the only one that really shows you any type of danger (unless you count a muffled voice). If Verbolten was painted with darker colors and maybe showed twisted dead trees instead of blossoming green ones, think it would help a lot with the overall them. I also think an effect like a shadow of a monster moving across the trees would be cool.
Anyway that's just my opinion on why Verbolten doesn't feel immersive to me. I still think it's a great ride and I really enjoy it, but it could definitely be improved.