Change a stock level
Add a portal to Goldwood’s first level that leads to your planet, without replacing the level. Your pack carries only the change, so it works with every player’s copy and alongside other packs that change the same level.
Start an edit of the level
In the Project window press Edit a stock level…, search for the level (Forest First is level 21), and
Create. Studio makes a level folder with base: stock:level/21.
Find your way around
The level’s own objects show in a dim blue in the Scene: you can see them, not select or change them. Fly to the spot you want; the new-game start point is a good landmark.
Add the portal
From Prefabs, drag in an exit (Players & exits) and a glow (Lights & effects) so players can see it. Set the exit’s Leads to to your level and its start point.
Optionally change the level’s look
The Level window’s fields write over the stock header: fog, sky, music. Leave them alone to keep the level as it was.
Play
Play starts the game in that level with your pack loaded; walk to the portal.
What happens in the pack
Studio writes your change as a patch of the level’s object list, not a replacement: an append of your objects. Another pack can patch the same level and both apply. A patch that expects an object the player’s data doesn’t have is skipped and logged instead of breaking the level.
The example world’s forest_portal level is exactly this: a portal, a glow and a light added to Forest First.