How feasible is it have two parallel dimensions in a single platformer layout?

My plan for implementing parallel realities is simply to have the two levels overlapping in a single layout and switch the visibility and collision of each as the player switches from one reality to another, probably through a placed portal.

I want my game to run on any regular browser but I'm worried that essentially having two levels on the screen at the same time may cost too much memory, or something.

I'm sure just having a layout for each dimension would be simpler and less resource-intensive, but I want the dimension-switching to be as fast as possible.

Anyways, my question is: is this approach too much, or is there a better one that is still very fast?

Both methods have their disadvantages.

You can keep both dimensions in the same layout, in many games the performance impact will be minimal. However, you will have to keep these dimensions separated, for example on different layers. Also, you will need to disable everything for inactive dimension - collisions, solids, stop enemies etc. And you will have to remember filtering out inactive dimension in all events. For example, when picking enemies - only pick instances on a particular layer.

With switching layouts there is a problem of syncing. You'll need to give Persist behavior to all changeable objects, remember player's position etc. Also, if you have a lot of graphics, there will be a delay when switching to another layout, which you'll have to mask with some transition effect like fade in/ fade out.

Thanks for the reply. Didn't know the performance impact would be minimal, which was my big worry.

Well, it's just an assumption, I don't know your game. If both dimensions mostly share the same objects and images, then it should be fine.

Hello, I'm also interested in this topic, what I would like to do is sort of a platform level that has a pristine state and an old and damaged one, the player will be able to see one or the other at will.

Another way of seing this is the remake of Monkey Island, where you can choose between the old low res graphics and the remastered ones at will and instantly.

almostdarkslide

Another way you could achieve this, provided the actual layout of your level isn't changing is to just switch animation frames or tile-map tiles. So your pristine world sprites are all in animation frame 0, and your destroyed world sprites are in animation frame 1. You could then dress up the transition in any way that you wanted, if you even wanted to.