There are two solutions - at first glance both solutions probably look long and very complicated, just take either of them one step at a time and you'll be just fine, any questions, just ask:

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1: N.B. only try solution #1 if you have plenty of food/water/oxygen, otherwise go to solution #2 :

If you're in a remote portal location you can use your jetpack and F4 to get outside the edge of the map.

At which point carefully drop down to the point that you can access the space underneath what would have been ground level (the space that portal wrecks normally occupy).

Presuming that space hasn't also filled in use your jetpack and F4 to navigate towards the pink beacon that indicates where the portal gate is.

Once directly underneath the pink beacon/portal gate, use F4 to climb up through the ground until you enter the portal which will hopefully still work to send you home.

If this solution doesn't work, the next step will be to save edit yourself back home...

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2: Firstly, save and close the game to the main menu.

Next, if you're on a windows computer browse to the following folder:

C:/Users/[username]/AppData/LocalLow/MijuGames/Planet Crafter

Note that the AppData is a hidden system folder, you may have to enable the option to 'Show hidden files and folders' to view it.

In that folder will be all of the save files in .json format, change the folder view to 'Details' and then sort the list by 'Date Modified', the affected save file should now be the topmost .json file on the list.

Open that file in a text editor like Notepad or Notepad++

Once the file is open, look for line 9 that starts with the data tag {"id": followed by a long 17-digit number, and ends with the data tag "planetId": followed by the name of whichever world you entered the portal gate from, e.g. Prime, Humble, etc. - this planetId name is important, remember it for the next step.

The fifth tag on that line is "playerPosition": followed by 3 coordinates each separated by a comma. To get home you'll need to change those 3 coordinates, thus...

If you're on Prime, you'll need to change the coordinates to "885,30,725"

If you're on Humble, you'll need to change the coordinates to "-145,165,120"

Now save the file and close the text editor. Back in the game, reload the affected world and you should hopefully now be out of the remote portal location and somewhere near home. Save the game at this point and you can continue to play.

Good luck.