This is the Trial game engine[1]. I've been using it recently to making a small game[2], and can say it's quite nice to be able to hot reload functions to test logic, collisions, etc. without having to restart the game. The Trial author has been working on porting it to the Switch to expand the reach of the game Kandria[3] (and other future CL games).
[1] https://github.com/Shirakumo/trial
[2] https://github.com/fosskers/save-the-farm
[3] https://github.com/Shirakumo/kandria