Data Pack made for the Flaming Pack Jam challenge:
https://www.planetminecraft.com/forums/pmc/events/flaming-pack-jam-resource-and-datapack-contest-657945/

The difference is like Day and Night

This data pack adds 2 new ores that generate in the Nether and End respectively (well, I say "new" but really they're just repurposed vanilla ore blocks). Sunstone ore generates deep underground in the Nether, roughly around Ancient Debris level. Moonstone ore generates in the End in the lower half of the islands.

Using these ores, you can craft Timepieces, which are consumable items that let you alter the time at will! When a Sunstone and Moonstone are combined with an Echo Shard, they form together into a Paradox Shard, which has its own unique properties! All three of these celestial stones can be crafted into block forms (which replace chiseled nether bricks, cracked nether bricks, and petrified oak slabs... its the unfortunate limitation of a less advanced data pack creator).

As a reference to Pokemon, Sunstones, Moonstones, and Paradox Shards have evolutionary properties... some mobs will change if you toss the item onto them! Frogs change variants based on which stone you use, allowing the player to interchangeably switch their color at the cost of a somewhat rare item. Foxes can switch to Snow Foxes, Cows to Mooshrooms, and even Allays to Vexes! I won't list every possible evolution, so you'll have to experiment yourself (just note that most evolutions are irreversible and sometimes even dangerous).

Totems of Undying are now more accessible, craftable using Sunstones... and, a brand new Totem is thrown into the mix: the Totem of Transience! This totem (craftable with Moonstones) is much like the polar opposite of the Totem of Undying. When held in your mainhand or offhand, it gives the holder massive buffs, but also inflicts them with withering that will quickly kill them if they hold it for too long (this effect applies to mobs that hold them as well, not just the player).

Paradox Shards can be crafted into a special compass called the Unstable Waypoint. When this is used, it will teleport the player directly to the Nether, in the EXACT coordinates they were standing when they used it (roughly). Take caution when using it, as it will drop you off in the middle of a wall or a lava ocean more often then not! To compensate slightly, it also gives the player near invulnerability upon entry, usually about how long it takes to load in the area.

Also has custom advancements! :D