The games introduced many new features including the Dynamax and Gigantamax mechanic, which causes a player's Pokémon to grow to a significantly larger size and use more powerful attacks in battle.

Random encounters with wild Pokémon typically occur in tall grass or bodies of water along routes and they might chase or run away from the player depending on their disposition.

[10] Other new mechanics include "Poké Jobs," which tasks the player's Pokémon with completing requests around Galar to gain experience or rare items.

[19] Sword and Shield are set in Galar,[20] a fictional region inspired by the United Kingdom,[21] with several of its landmarks resembling places such as Bath, Somerset and York.

[24] Many of the region's towns and cities feature Pokémon Gyms stylised like football stadiums, showcasing the games' Dynamax and Gigantamax mechanic.

During their subsequent visit to the region's Pokémon Professor, Magnolia, and her granddaughter Sonia, they convince Leon to endorse the player and Hop to take part in the Gym Challenge.

The player also meets Chairman Rose, who, in addition to endorsing Bede as a Gym Challenger, presides over the Galar League and the region's main energy company, Macro Cosmos.

After beating the eight Gym Leaders, the player makes their way to Wyndon where they win the Champion's Cup, earning an opportunity to battle Leon.

The game's post-game has the player and Hop confront Sordward and Shielbert, two brothers who attempt to drive Zacian and Zamazenta berserk.

Shigeru Ohmori, who previously directed Sun and Moon, formed a team to brainstorm ideas for the title.

One of the first ideas the team had was making Pokémon gigantic in size to capitalize on the Switch's high resolution and TV connectivity.

Similarly, they considered allowing the player to freely control the camera to enhance the games' exploration experience, before consulting the staff members in the form of an internal debate, and it was ultimately included.

They designed the Wild Area as a "wide-open space" that is different from the traditional route systems and is constantly changing where "it would be interesting to come back every day and see what has changed—something that would feel different each time.

[33] Ohmori stated that they included fairly short loop tunes for the route music, as opposed to the longer, more dynamic songs in the Wild Area.

[16][35] Producer Junichi Masuda addressed this as a potential issue in a 2018 interview with GameSpot, saying that "it does get complicated when you talk about the details and we're still figuring it out, but we do have plans to find ways to let players use their Pokémon in the next game.

[39] Sword and Shield were first teased through a special message by The Pokémon Company president Tsunekazu Ishihara during Nintendo's E3 2017 presentation, where Ishihara mentioned that Game Freak was working on a new core series Pokémon role-playing game for the Nintendo Switch but that it would not be released for more than a year.

[43] Game Freak intentionally limited the number of new Pokémon they revealed through promotional materials to encourage players to discover them in-game.

[45] A 24-hour livestream released in October, set in the games' Glimwood Tangle location, led to the reveal of a regional variant for the Pokémon Ponyta.

[46] A promotional crossover between Sword and Shield and Tetris 99 occurred from 8–11 November, during which a limited-time unlockable theme based on the games was available.

[55] During the Pokémon Direct on 9 January 2020, an expansion pass was announced consisting of two parts, The Isle of Armor, and The Crown Tundra, and they were released on 17 June 2020 and 22 October 2020, respectively.

[56] The expansion pass added additional storylines, locations, characters, new and returning Pokémon species, and other features not present in the base game.

[61] Similarly, Casey DeFreitas of IGN praised their engaging gameplay, complemented by compelling battle and exploration experiences.

Despite this, he felt that the game did not take full advantage of the Nintendo Switch's more advanced hardware, and found various visual aspects underwhelming.

[e] In their review for Eurogamer, Chris Tapsell criticised the games for their lack of depth, absence of complex dungeons and intricate lore, limited exploration option, and a restricted Pokédex, creating an illusion of scale and ambition that ultimately fails to provide a satisfying Pokémon experience of depth and substance that characterized previous iterations.

[64] In their GQ review, James Grebey and Tom Philip criticised their lack of challenge, depth, and innovation, expressing disappointment in the games' execution and their failure to fully utilize the capabilities of the Switch.

[65] The decision to exclude many pre-existing Pokémon in the games drew criticism from many fans, who referred to it as "Dexit", a portmanteau of "Pokédex" and "Brexit" (tying in with the Galar region's British theme),[71] and used the hashtag "#BringBackNationalDex" to discuss the matter on social media.

[72] Fan backlash focused on the removal of a long-standing aspect of the franchise, the discouraging of its former English tagline "gotta catch 'em all,"[72][73] and a perceived lack of improvements in other areas of the games, such as graphics and animations.

[75] Writing for Polygon, Patricia Hernandez commented that "to some degree, the backlash makes sense" while adding that it had "gotten out of hand".

[71] Masuda formally responded to the criticism on 28 June 2019, two weeks after it erupted, expressing appreciation for the love and passion shown by fans.

During its opening weekend, Sword and Shield had sold more than six million copies worldwide, surpassing Super Smash Bros.