Game engines create the potential for amazing, complex experiences.
A diamond hard, efficient, resilient underlying game engine.
And then most of a game's logic is implemented in squishy, easy-to-prototype logic like Lua.
A hardened foundation for open-ended creativity on top.
A good two-layer shape for many open-ended generative systems.
Web development: diamond hard runtime of the browser, soft and squishy web apps on top.