This was on hacker news a few days ago but there wasn't much interest, which is surprising.

Setting a data breakpoint, then rewinding time, then fixing the error in code (while game is running), hot-reloading code and continuing the run with it fixed. All from a recording of a panic dump from another user.

This is next level stuff. Extremely impressive.

Wow I'm just 5 mins into the video and this looks ridiculously powerful. This is essentially an integrated development environment for game development with everything every programmer dreams about!

How do I learn to make such tools? From what I heard everything in the video is built in-house including the language and compiler. Although I understand many game studios do similar stuffs this is by far the most impressive I heard about.

Great demo! The article also has a link to it.