I don't think that there is a simple way of creating 2.5D platform behaviour in C2. 2.5D physics must be applied to events etc. I'm working on a 2.5d game right now which involves platform behaviour in stage 2. When i reach to that point i'll be able to spend time on figuring things out and put my ideas in place. If i have a breakthrough i'll post it here.

I updated the capx by applying bounds, enemies and collectibles.

dropbox.com/s/l54dt3x85wcfrha/25D_Platform_Movement.capx

I'm currently using the free C2 version so i could not group the objects in families etc. but you get the general idea.

The enemy movement is a brain teaser though.

Haven't worked on that yet. Maybe someone could share some ideas.

The bounds are easy enough to appy by limiting the platforms' Vertical movement within certain bounds. As for the enemies, they might have the 8 dir behaviour and their collisions disabled and put on another layer, but then they wont be able to follow the player in different platforms...

The thing is that in a 2.5D platform game the player should fall off the edge of the platform if no collision is detected and be able to jump on another higher platform as well if needed. How can this be applied to your example Tokinsom? That's realy an interesting topic:)

Oh i forgot, use WASD to move,space to jump...

After giving it a thougth i came up with this solution by combining platform width custom behaviours.

dropbox.com/s/l54dt3x85wcfrha/25D_Platform_Movement.capx

its just a basic approach but it can be extended according to your needs.

I would realy love to see an answer to this as well....The only post i found addressing this issue to a certain point is scirra.com/forum/25d-jumping-proof-on-concept-need-help_topic62057.html. But still the player cannot retain his platform behaviour on top of the box...