itch.io

Hi! Thank you very much for your feedback!
As soon as I can, and at the end of the jam ,I'll clean the source code since it is REALLY messy... but you can find it in my github page.
Since I didn't find lots of tutorials out there about the things you asked me, I'm really glad you posted your questions.
The fading effect of texts, buttons and images in the titlescreen is created via the AnimationPlayer node.
Actually to fade things you could simply use a tween and change the modulate property of node, but since I also wanted to displace things and add more background effects I decided to change properties like position, modulation and sizes via AnimationPlayer.

The changing scene effect with the circle changing size is a little bit tricky:
I think that the youtuber GDquest did something similar, but I had to use another solution because I needed to load and even edit different things at the same time.
The black circle is just a ColorRect with a random color and a shader with a mask applied. With some parameters of the shader I change the size of the circle, and to change these parameters I use an animation player.
The circles are actually two: one is used just to open the view in the title screen, the other circle is an indipendent Scene which I use as a singleton and animate separately. In this scene I use an AnimationPlayer too, because I call some functions from the animation player itself to load the level which is procedurally generated every time.

I know that a practical example of these things could be useful, but it is really hard to explain some mechanics in a simple comment and I'm not good at tutorials. Take my answare as technical , there is a lot of stuff on internet that could help you do the same things, and if you want check out my source code (I just don't recommend it since it is hard to understand something that is not written by us or commented to explain things).