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Making a multiple universes game with multiplayer

Hi everyone!

I’m been thinking for quite some time about doing a game with multiple universes inside. Something like a parallel universe with a similar layout but different features each. For those of you that played it think Metroid Prime 2 : Echoes. The players can switch from one universe to the other almost at will independently from the others. And they can only interact with and see what is in the same universe as them.

The level streaming seemed like a good idea for this with the persistent level having common collision info and each world loading/unloading using some code. The streaming volumes were discarded since both universes have to overlay each other.
But when thinking with multiple players this concept does not seems to work. As when one player changes universe that would hide the previous universe and show the new one, effectively moving all the players from one universe to the other instead of just the one.

Well, I have not yet tested all of this (I don’t have access to my computer at the moment) but if anyone has done it I would be thankful if they would let me know how it went.

Well, Echoes did it the cheap way and had a dark and a light version of each area and you jumped back and forth between them through portals placed within the world.
So they were able to mask the loading of the new assets with the transition sequence and it only needed to load the room where the portal was located in and do the rest of the area loading room by room through level streaming.

If you wanna be able to switch between two universes at any time and in any location you need a different approach for sure.
In the end both versions of the level might have to be loaded all the time and one of them will have visibility for the player turned off.
Otherwise the loading/unloading/streaming of assets during a match could lead to noticable transition times.

Also it hugely depends on the gameplay and pacing of your game.

A quake like Arena shooter might need a quite different approach then a slower adventure-like game in huge linear worlds where you solve puzzles with the help of other players.

Blizzard does this using ‘phasing’ in World of Warcraft. There are some zones that look different in both landscape and object placement, but also the players and NPCs are different, as well. To do this I believe they create multiple maps and then load the appropriate one for the player. There is a small transition, but on most modern computers it’s only a few seconds if that.

i did something similar two years ago to get into uni, i had a side scroller with a teleport to another time, i had the main level as the base timeline and another level below it as the darker, more dystopian timeline. had no idea how to use streaming levels, so i literally duplicated the whole level, moved it down and used a trigger volume to hide the other level depending what side the player was on. it worked pretty well and worked with multiplayer. i even had objects that could be moved in the normal timeline that also moved in the dystopian timeline, it was just a lot of tricky logic.
i will try to find a vid of it all working, currently i only have the teleport on youtube.