Scorched Earth adds 12 new creatures with 5 variations, 60 new engrams, a new boss, and a whole new map.
Creatures tamed and items received can be brought to the vanilla island and used by people with and without the expansion. Items from the DLC can also be spawned manually if you don't own the expansion pack. Three of the new creatures have multiple variations, namely the Jugbug (Water and Oil), the Wyvern (Fire, Lightning, and Poison) and the Rock Elemental (Rock and Rubble).
Being entirely a desert rather than an island surrounded by water, water collection becomes a more challenging obstacle. Natural water sources are rare, requiring the collection of water from other sources, such as cactus, water wells, Jugbugs, or Morellatops. Heat stroke is a potential side effect of too much heat exposure, having a similar effect to being drunk. Also the naturally harsh environment damages generators and certain structures.
Scorched Earth has three unique weather patterns: Sandstorms radically reduce visibility and drain stamina, Superheat will drain your water at a much faster rate than normal heat and induce Heat Stroke fairly quickly, while electrical storms will temporarily shut down electrical devices and prevent firearms (and Tek Saddles) from firing. The Electrical Generator and the Chemistry Bench will not turn off if the item Structures are covered.
Superheat can be quickly stopped if you go very close to the Oasis. Desert Goggle can be used to see better during sandstorms.
Scorched Earth adds 3 new Artifacts, which are needed as part of the tribute to summon the Manticore.
Scorched Earth was the first Expansion Pack for Ark.
Scorched Earth was the only Expansion Pack to be released before the actual base game was finished.
Scorched Earth was the only Expansion Pack that wasn't delayed.
Interestingly, the Manticore is the only Guardian ever shown on Scorched Earth. It's unknown what happened to the other two Guardians.
Scorched Earth is the only Expansion Pack to have Trophy Heads of Alpha Creatures.
Scorched Earth is the only Expansion Pack that doesn't have an ending.
There was a planned Ascension cutscene where the player would be taken to Aberration ARK, much like how defeating the Overseer takes you to Scorched Earth, and how defeating Rockwell in Aberration takes you to Dead Earth in Extinction.
Wildcard has confirmed that Scorched Earth is considered complete and no further plans are set for the DLC as stated in one of their livestream: "when we released it, we released it as a finished product, ultimately ascension was planned for The Island but not Scorched". This may mean that Ascension addition will never happen in Scorched Earth, nor will there be any major update for the DLC excluding the recent changes to the Thunderstorm Weather and the addition of the Phoenix.
The DLC has been released while the base game was still unfinished, leaving the transition to Aberration unexplained.
Many of the Scorched Earth creatures and items can be found on the Ragnarok map, except the Phoenix.
Scorched Earth is the only Expansion Pack to not have variations of previously existing creatures.