No more than 255 tiles?

[pleegwat]

If every byte was set to the true 64-bit integer (1 decellion), this game would need ~200 TB of memory. So that is why these practical values exist.

No, 64 bits can index 2⁶⁴ or about 16 * 10¹⁸ tiles. In words this is sixteen trillion or sixteen pentillion, depending on whether you subscribe to the long or the short scale. This is nowhere near a decillion (10⁶⁰ or 10³³, depending on the scale). However, this is completely irrelevant. The relevant number is 8 bytes per tile (or 8 kilobytes per chunk) for the tile IDs, plus some memory for those tiles which have been assigned a meaning. There is no need to allocate memory for unused tile IDs.

[FuryoftheStars]

As part of the Space Age work we had to bite the bullet and change tiles to support up to 65'000~ tiles. It means more memory used and potentially save file size but it's now going to be there.

HECK YEAH!!!! \o/

Out of all the changes to the game for 2.0/expansion, this one right here is getting me the most excited!!