This is the best open source game engine I've come across in a decade! I just love it and the python-like scripting lanaguge they call GDScript (GodotScript). It's especially great for 2D games but is also making great strides in 3D development and graphical fidelity. Modern features like a Vulkan backend and export to basically any possible platform are already present and it is constantly evolving to be one of the best engines out there!

And all of that is completly free forever, no upfront or long term license costs at all!