Upon request, here follows a more detailed list of the revisions.
4 phases: The Arkham Encounter phase and Other World Encounter phase have been merged, and Upkeep has been renamed Rest.
Easy evade: Combat ends after having made a Combat Fight or Combat Sneak test – regardless of the result.
New monster symbols: All dimensional symbols have been renewed, and multiple were merged (dash+star+triangle, and diamond+square).
No Monster/Gate limits: There are no more limits, which also means the Outskirts have been removed.
Quick final battle: During the Final Battle, each turn, only the Lead Investigator attacks. However, each hit reduces Doom, one-to-one.
Scenarios: The expansions have been remade into 6 scenarios, with clear definitions of how they change the gameplay. They include: Black Goat of the Woods, Curse of the Dark Pharaoh, King in Yellow, Dunwich Horror, Kingsport Rifts, and Shadow over Innsmouth.
Less locations: Stable locations without abilities have been removed (Newspaper, Velma's Dinner, and Library). All Other Worlds have also been removed, and the Outskirts and Sky as well.
Vortex: The Arkham board now also has vortices (instead of the Outskirts and Monster limit).
Areas: Neighborhoods have been merged into areas; 5 in Arkham, and 2 in each of the other towns. Each area has its own Encounter deck.
Location icons: Only unstable locations, depot locations, and locations that close as Terror advances, now have icons on them. Aquatic locations have a wavy border.
Awaken: Instead of a Doom track, the Awaken value is used to check if the Ancient One awakens.
Easier abilities: Ancients Ones with abilities that require players to memorize values have been altered. Example: Cthulhu now longer permanently reduces maximum sanity/health every time the investigator goes insane or is knocked unconscious.
No followers: The buffs to specific monsters, per Ancient One, have been removed.
Battle actions: Two of the Battle cards have been incorporated on the backside of the Ancient One card.
Fixed skills: Investigators no longer have skill-sliders or Focus. All secondary skills have been renamed for ease-of-play: Combat Fight test (Combat check), Combat Sneak test (Evade check), Combat Will test (Horror check), Spell Lore test (Spell check), Walk Speed (amount of steps the investigator may take per turn).
Setup info: All setup rules have been moved to the backside and simplified.
Refined abilities: Most had to be adjusted to match the other changes to the game rules, others were made to work in all phases or otherwise made more open.
Trish Scarborough: She has a special token with different skill values on both sides, allowing her to change her values.
Setup info: Again all setup-related information has been moved to the backside.
Refined abilities: Changes to specific Ancient Ones have been removed.
Lurker at the Threshold: No longer allows a Pact to be made. Instead, grants a single Power token when successfully casting a spell, and takes it away when failing at casting a spell. The Power token allows the player to use sanity/health as clues. Reckoning cards remain.
All Guardians: Institutions have been renamed to Guardians. Like Heralds, their setup-information has been moved to the backside.
Refined abilities: Location-specific requirements have been removed.
Bureau of Investigations: No longer adds Agent tokens, but instead investigators can spend clue equal to double a monster's toughness to defeat it.
Less decks: Because neighborhoods were merged into areas, there are less individual decks – each deck holding 5 or 6 locations. One encounter deck holds 3 locations, the Cult encounters, and the Exhibit encounters. Innsmouth's Jail Cell encounters now have a Sneak test, instead of first testing it to determine the amount of cards drawn.
Less cards: Only the top 29 encounters from each location have been chosen, resulting in 30-card-decks.
Scenarios: Encounters that are scenario-specific are marked as such with the scenario-icon.
Shuffling: Players no longer shuffle each time they draw. Instead, each deck holds a The Story Continues… card that instructs the player to shuffle the deck.
Neutral allies: Encounters no longer instruct players to look for specific ally cards, and instead instruct the player to draw the top card.
One world only: Because Other Worlds were removed from the board, each card shows only one specific Other World location.
Tiered encounters: Each card holds 3 encounters; Gateway for when the player first explores the gate; Mystery for when the player has completed a Gateway encounter and placed a Mystery token on his gate; and Explored for when the player was allowed to place an Explored token on his gate.
Closing gates: The test for closing a gate, and all the results from that takes (ie. removing monsters), have been included into the Explored encounter on each card.
Shuffling: Like normal Encounter cards, the Other World cards also have a The Story Continues… card to indicate the deck must be shuffled.
Two parts: Each Mythos card has two sides. The lighter side is related to a specific scenario, indicated by the centre icon. The darker side is used only when the listed scenario is not in play.
Action order: The effects of each card is listed in icons, starting top-left and continuing to the right and bottom, ending with the text effect.
Gate icons: Because gate tokens now hold the destination for the gate, all the Mythos card holds is an icon to indicate a gate must be opened. There are also icons for gate bursts, advancing doom twice, and monster surges. The later of which was added because gates can no longer open on the same location.
Effect types: Headline has been renamed Event, and all types of Environment cards have been renamed Conditions. Rumors remain unchanged.
Monster movement patterns: Predictable sets of dimensional symbols have been removed, for a random-looking appearance of symbols on each card.
Types & names: Common Items have been renamed Assets, Unique Items have been renamed Artifacts, and all unique investigator cards have been put into a single deck; Special.
Tags: Each card has tags indicating the type of card, in the top-right. A single card can have multiple tags (ie. weapon+magical+item). These tags are called for in abilities and effects (ie. "Discard a weapon.").
No duplicates: Except for 3 Elder Sign cards, no deck holds duplicates of any card.
Sanity cost: Spells only cost sanity when failing the Spell Lore test – there is no 'starting cost'.
Double sided: Each token has different values on both sides, reducing the amount of times players have to go 'fish' for tokens.
Skill token: Skill cards have been removed and replaced with tokens. Each token simply increases the matching skill by 1.
Counter token: All variable tokens that were only used by specific Ancient Ones, Heralds, or Guardians have been replaced by a single new type of token: the purple Counter token.
Track markers: Each track found on the board has a single marker to gauge its value. Including Doom, Terror, Calling (for Dunwich), and Rising (for Innsmouth).
Town tokens: All tokens that are added to specific locations have been made in the same shape.
Gate explored: The Explored gate token had been replaced with a double-sided token. One side shows the Mystery token which is added after having had a single encounter. The other side shows the Explored token to which the token is flipped after the second encounter. The side the token is on determines what encounter on the Other World Encounter card the player uses.
Hypnos: A Hypnos token has been added to indicate the 2 locations his ability applies to.
Special tokens: All tokens that are only used by specific Investigators, Ancient Ones, Heralds, or Guardians now have the same shape. The rules of the token is often listed on the token itself.
Dust: The Dust cards have been replaced with Dust tokens.
Being of Ib: The Being of Ib monsters have been turned into tokens, since they weren't allowed to be attacked anyway.
Gate locations: The only thing a Gate token shows is its location on the board (in town).
Rifts: These tokens no longer have the rule that Doom advances when moving along the same colour.
Refined abilities: The Ambush ability has been removed. Elusive monsters simply state that they may be freely evaded. Physical/Magical/Weapon Resistance and Immunity has all been replaced with Resistance – which ignores all bonuses from non-magical items.
Movement colours: Stationary movement is now white and Unique movement purple, Flying movement is green and Aquatic movement is blue.
Movement types: Stalker movement has been merged into Fast movement. Flying monster do not move to the Sky but may instead consider all streets adjacent. Likewise, Aquatic monster may consider all Aquatic location adjacent.
Epic monsters: Spawn monsters have been renamed Epic, and their shape is equal to normal monsters with the additional of spikes on all sides.
Patrol: Patrol tokens have been made into Epic monsters.
Ancient Whisper: Likewise, the Ancient Whisper is now an Epic monster.
Duo boxes: The large box contains the game (including the smaller box). And the smaller box opens up into two halves: one to form the monster pool the other to form the gate pool.