Elon Musk just gave shares in Poland’s biggest computer game maker a turbo boost, by enthusing over CD Projekt SA’s Cyberpunk game on his Twitter account.

The company’s stock soared as much as 19%, the most since June 2015 and with trading volume nearly six times its three-month average, after the Tesla Inc. chief executive officer tweeted Thursday that “the esthetics of Cyberpunk is incredible.” Hours earlier, the billionaire had tweeted that it would be possible to play the complex and futuristic game on Tesla’s new Model S Plaid.

CD Projekt shares have surged this week along with some of Europe’s most-shorted stocks in an echo of a similar rally in the U.S., where retail investors have battled against short-sellers by piling into names like GameStop Corp. The Polish game studio has soared more than 40% in four days.

Glitches in the company’s eagerly awaited Cyberpunk game, launched in December, prompted Sony Corp. to drop the title from its PlayStation store in an unprecedented move for the industry. But short interest in the shares has started to fall back from the record 10% level seen at the start of the month.

Melvin Capital Management LP has been among the funds with a short position on CD Projekt’s stock.

Musk first showed interest in CD Projekt’s biggest ever production in 2019. Soon after the game was unveiled last month, he tweeted that he briefly played it and that it “seemed pretty good.”

And the Polish game maker isn’t the only stock to have benefited from Musk’s tweets this week. On Tuesday, Etsy Inc. shares jumped as Musk praised the company after he bought a gift on the e-commerce platform for his dog.

CD Projekt’s stock, which had plummeted after Cyberpunk’s troubled debut, ended the session 16% higher. The studio released a major patch over the weekend to address bugs in the game, followed by a smaller fix on Thursday.