I've had a lot of fun with Godot. First, I got familiar with GDScript and made a moving character. Then, I improved that initial character and also interacted with physics objects.
Now, I've made my first useful program. The same character can now plow into 3D shapes with accurate physics simulations.
Want more? For those of you with more... powerful computers, I've made another physics simulator, this one designed especially to be mean to @DynamicSquid, which can be downloaded here. I can make Mac and Linux versions if you need, but I doubt I'll have to.
As a challenge, try pushing the objects into the void. The best method is to glitch them through the unproportionately thick and overlapping walls that do nothing, apparently. You can try pushing over them, but this is no easy task; I was too lazy to add a roof but the walls are pretty high.