Unreal Engine 4 - GT.TV Exclusive Development Walkthrough
Why Hacker News recommends it
HN cites it as a favorite demo of live coding and hot reload in a game engine.
What it is
A GameTrailers walkthrough from E3 2012 of an Unreal Engine 4 real-time tech demo with Epic's Alan Willard. It shows live code changes and hot reloading while the game runs.
Recommended by 1 HN commenters across 1 different months, 2015 to 2016.
What Hacker News said
Strong rec archivator · 2015-03 · on “Unreal Engine 4 is now available to everyone for free”
This is my favorite Unreal 4 demo - [this video] (sadly missing the wonderful quote "I light my level by dropping a sun in.") I'm completely in awe of the feedback loop here. It even compiles and swaps code while you're in the game!
Cites amadeusw · 2015-08 · on “Working Toward Bret Victor's “Learnable Programming””
A few years ago (2012) I was taken aback by the Unreal Engine development process. Their IDE features a running game with all elements being selectable and interactively editable. In one video fragment [1] they hop to Visual Studio where they change gravity. After a few seconds of compilation, the game's code is updated. [1] [this video]
Cites binthere · 2016-12 · on “Choosing Functional Programming for Our Game”
I believe that on Unreal Engine 4, you use C++ and it does have a feature that mimics "live coding" where it recompiles and hot-reload your game even while playing. edit: here it is [this video] (jump to 9:40 if it doesn't load at this point automatically)