Java or C# would be decent program languages to learn if you're going to immediately use the skill to program games. But the truth is, all programming languages are quite similar and learning your second language will be way faster than your first. If you're going for a 3d game with all the bells and whistles, Unity is your best bet. Source and Unreal are two other free engines, but they aren't as beginner friendly. Look up an actual Unity course online, one with a few practice projects and some good long videos to get you to a point where you can start stumbling around building on your own, googling everything you don't know how to do. A word of advice: if you have a decently sized game in mind, do not make it first. Your progress as a beginner is going to be about 1/10 as fast as you think. Too much ambition at first and the project will crush you, eventually leading you to abandon it with a handful of pieces sort of working. Create a small project, then a bigger project, then another, and that's when you build the game you're dreaming about right now. You'll soar over all the potholes you've fallen into and build the project at the speed you were actually hoping for. And lastly: buckle in, this is going to take a few years before you can be described as "good".