This depend on the kind of legal relationship one has with the company. If you’re working as independent contractor with a B2B arrangement, the notion of overtime does not really exist. If however you are employed through the “employment contract” (“umowa o prace”), the limits on overtime are really strict, and you must be paid for it, in fact 50% extra, and double pay for overtime worked during nights, sundays and holidays.

I don’t know what’s the typical arrangement in game industry, but in software engineering industry at large, B2B contracts are very common, due to rather preferable tax treatment. B2B gives 10-30% increase in net pay, and its downsides are lack of mandatory severance, mandatory time off days, overtime pay etc. In most scenarios these are not an issue, because if one can negotiate high pay justifying B2B, one can also negotiate time off and lack of overtime. Don’t know about game industry though.