There are a lot of free alternatives; monogame is nice, http://www.godotengine.org/wp/ is recent and there is a lot more. Unity is very popular and nice, but if you want to try/play around/make simple games there are alternatives enough.
Sure, GDScript is poorly documented and isn't really python, but it's not that hard to find the undocumented features (search the github code), and the fact that it compiles to pretty much any platform means it's a rather small mental investment for a large gain in deployability.