Shares of Unity Software (U 1.42%) have been off to the races since the company's IPO in September. As of this writing, the stock is up nearly 60% from its debut just a couple months ago.

For students and personal use, Unity is entirely free and will remain so, if you're using it to make your own game, as long as you stay below a $100,000 threshold for funding.

Unity proclaimed that on Jan. 1 it would be implementing a pay-per-download pricing model to charge developers a flat fee any time someone installs a video game utilizing Unity software.