Dynamax, the Wild Area, and the great Dex cut.
Sword, Shield · Released 2019
Galar is the Gen 8 region, the first mainline Pokémon on the Nintendo Switch, and the most controversial generation in franchise history. Sword & Shield introduced Dynamax (temporarily gigantic Pokémon with rebranded 'Max' moves), the Wild Area (a semi-open overworld with free camera control), and Gigantamax forms. It is also the first mainline game where not every previous Pokémon is available — Game Freak cut the National Dex, limiting transferrable species to those with Gen 8 3D models.
Galar is based on the United Kingdom — Wyndon is London, the Stow-on-Side market is a Cotswolds village, Spikemuth is a grunge-industrial town in the North, and the Crown Tundra DLC is the Scottish Highlands. Zacian and Zamazenta reference Arthurian legend (the sword and shield of British mythology).
The 'Dexit' controversy (Game Freak cutting hundreds of Pokémon from Sword & Shield) was the largest player backlash in franchise history. Director Shigeru Ohmori publicly apologised, and Gen 9 Scarlet & Violet expanded the roster back with DLC — but Gens 1-7 have still never been fully returned to the main series.