Sega claimed they had no choice to use Unity, but there's controversy around that position.
This past weekend, Sega released its first crop of free-to-play classics through its new Sega Forever service on iOS and Android: Sonic the Hedgehog, Comix Zone, Phantasy Star II, Kid Chameleon and Altered Beast. Although many people (including me) were excited to replay some of their favorite games from the company's history, these mobile ports are plagued by awful frame rates, frequent stuttering, sound hiccups, and more.
The fan reaction has been appropriately sour, but Sega has still defended what it calls a "really positive" launch in a bruising interview with Eurogamer.
The interview questions why these dated games can't perform on modern hardware, why the old mobile ports of these games could run better seven years ago, and why Sega went with the Unity engine over a better emulator. Sega didn't give much in the way of substantial responses, but chief marketing officer Mike Evans did say that Unity was chosen because it allows Sega to "bring these games to the largest audience possible… especially in developing countries."
However, Digital Foundry and others claim that Unity is the reason why the emulation is so bad, and that a different emulator called RetroArch would have worked much better.
RetroArch developer Libretro have come forward and stated that Sega approached them with the idea of using their emulator for Sega Forever, but the company "demanded we relicense our program to something that would strip us of all our rights." Indeed, Evans mentions that "from a Sega perspective, we can't bundle GPL software with Sega proprietary games, because we lose certain rights within the games—it's a corporate policy for us."
While building an early demo of Sega Forever for Sega, Libretro also says that they had to fight to get any kind of recognition or branding shown in the games. "It seemed like there was a lot of reluctance to acknowledge that [we] were powering this application," developer Daniel De Matteis said in a statement to Eurogamer. "In the end, for that demo we were eventually allowed to show the branding at the splash screen, but in our mind we shouldn't have to even had to insist on it to begin with." You can read the full statement here.
This whole situation seems to underscore modern Sega's ambivalence toward its own classic history, where it's something to be appreciated and acknowledged, but not necessarily cared for.