Scaleform
Middleware that ran Flash files inside game engines, so menus and HUDs could be built by artists rather than programmers.
Game interfaces used to be hand-coded: every button a line of C++, every animation a change that needed a recompile. Scaleform GFx let UI artists work in Flash, with timelines and ActionScript, and then played the result back hardware-accelerated inside the engine. Through the second half of the 2000s it sat behind the menus of a large share of AAA games.
Autodesk bought the company in 2011 and stopped selling the product a few years later. The industry moved on to engines' own UI systems and HTML-based alternatives. Flash's death in the browser in 2020 had, in other words, already happened in games — just more quietly.