(Reuters) -Poland's biggest games developer CD Projekt posted on Wednesday an 88% year-on-year jump in its first-half net profit, driven by higher sales of its flagship Cyberpunk game.

Net profit reached 170.0 million zlotys ($44.1 million), compared with analysts' forecast of 163 million zlotys.

Revenue for the period rose 31% to 424.8 million zlotys. Sales of "Cyberpunk 2077" together with its "Phantom Liberty" expansion jumped about 81% to 257.7 million zlotys.

CD Projekt said it is gearing up to start the full-fledged production phase of project Polaris, the first instalment in the new Witcher saga.

"Work on Polaris is progressing – its development team is nearing a major milestone which will mark the end of the preproduction phase," joint CEO Michal Nowakowski said in a statement.

"The first half of the year was also a busy period for our Boston studio, which is laying the groundwork for Project Orion – a new game set in the Cyberpunk universe", he added.

As of July 31, 410 developers were working on the new Witcher saga under the codename Polaris.

($1 = 3.8583 zlotys)

(Reporting by Adrianna Ebert; Editing by Mark Potter and Jan Harvey)