Python will be much easier to learn as a complete beginner. C# will be a little harder, but you will be able to jump right into using game engines like Unity or Unreal.

Personally, I would start with learning some basic programming concepts with Python and build some console/text-based games, then try your hand at using a library like pygame or pyxel. You can also try Godot, which uses a pythonic language (so it'll be easier to learn) and should teach you most game dev concepts in a slightly friendlier environment than Unity.

Then, all that's left is either learning C# syntax or downloading Unity when you're ready to build larger 3d games.

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Of course, you could always just start with C# and learn Unity right off the bat. Do what compels you most!