FYI they're not suing, they're just THREATENING to sue and betting on the dev not having the resources to fight them. Hell, the dev doesn't even have the resources to make the game without crowdfunding.
There is a Grady Hendrix horror novel set in a fictionalized Ikea store, whose cover is an obvious homage to Ikea catalogs and I don't recall them suing over that. Very strange.
An independent game developer is in hot water with Ikea for making a survival-horror game set in a furniture store bearing similarities to the popular chain's retail locations. While the developer says the game is inspired by a piece of horror fiction, Ikea has filed a suit to protect its brand.