A 4-minute video on some graphical debugging tools I've been growing. I suspect this is all old news to game programmers.
Built in Lua and LÖVE.
Source code for the right side: https://git.sr.ht/~akkartik/template-live-editor2 (650 lines)
Source code for the left side: https://git.sr.ht/~akkartik/driver.love (1500 lines)