Yes, I'm using Engine.time_scale for the most part, but also adjusting the music pitch_scale in the same function. I used a tween for the transition between normal and slow motion (as I learned in a very helpful tutorial). But sometimes the change of time_scale bothers other systems, so it's a bit hard to tweaked correctly. An easy fix for animations is to simply establish its playback_speed to 1/Engine.time_scale, so it always play with the same timing. Thanks for playing and commenting!