I don't believe in intellectual property, but to the extent that we live in a world where IP exists, the original game as described is pretty clearly using IKEA's trade dress.
It's still bad when mega-corporations attack small guy. Its certainly worth to shame companies for doing this kind of stuff.
And almost as comical as Nintendo buying rights to a porn movie to prevent their distribution:
ALDI/Lidl copy every big brand under the sun. They've been litigated against, but they get away with it way more often than they lose. Many cases fail to prove that consumers were misled, and (I find this incredible) one of the strongest defenses is that store has a strong reputation for brand imitation, so there is in fact no confusion. People go to Lidl to buy Neos, knowing full well they're not Oreos. It's also surprising that other supermarkets get away with it when they sell the copycat product next to the original.
If you could afford lawyers, you could definitely get away with that game, but it's easier for IKEA to stomp you.
I too am skeptical of government-granted intellectual monopolies, as Richard Stallman correctly names them. Trademarks are the least offensive of them because they expire relatively quickly and are designed to prevent genuine consumer confusion. Trade dress rules help prevent consumers from unwittingly buying products from Company A while thinking it's Company B.
This video game creates zero risk that a consumer will buy furniture from the wrong store, so trade dress should be inapplicable. IKEA would likely even lose in court. But as the article points out: legal proceedings ... get really expensive.
This move was pure bullying by IKEA lawyers.