The portal uses a series of commands in procedures to generate a portal in other Minecraft worlds (TheEnd, TheNether, Overworld) and defined modded worlds (SpaceRift:Paradise).
Portal locations are at the same exact place coordinate based so when you go to the nether you can actually travel farther depending on your distance in the regular worlds as coordinates don't change eg. 800 in the overworld will be 800 in the nether.
Randomly Generated Gatekeys
Gate keys are generated randomly per save, they are only generated once but are stored in the save using global variables. Using a complex math-based system to cross-check that gatekeys don't overlap with existing gatekeys during generation and making sure the four numbers are between 10 and 99 the gatekeys offer a stable and reliable method to make it harder for players to use the portal.
Gatekey Books can be found in ruins in three biomes types (Deserts, Swamps, and Jungles)
These books when right-clicked can reveal and save a random gatekey to your portal history list.
These books give an equal possibility for what world you may get, however, in the future, there may be a weight introduced for what worlds have a higher probability.
Portal teleportation is really complex using a few commands to make sure everything in the area of the portal blocks is moved when the portal is right-clicked while sneaking. This works with every entity even modded entities and will bring them to any desired world with you.
The history saves the last four book keys to your portal history tab, this can make it easier to get back and forth between worlds and only requires a book to right-click to save the world gatekey code. In the near future world, names will also be displayed before the code for easier filtering of keys.
The paradise dimension is a work-in-progress world that will have many biomes, plants, and structures. At the moment it's just a rough outline of what the vision I have for the dimension will be once it is done. Future dimensions will be theme-based and have entire ecosystems blocks and reasons to travel to those worlds. Also, specific worlds may offer gatekeys that are only unlockable through specific ruins in such worlds this will be part of the progression for exploration of course in the future.