I said this in another thread just now, but the great thing about "what should I make" questions is that companies routinely broadcast to the world exactly what they want to see, in the form of job advertisements.
I just picked 6 random junior game developer job ads here in the UK and here are their "required skills":
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Interest in videogames and gameplay development (x3)
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Unity (x2)
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good OO programming knowledge (x2)
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good C++ skills
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good applied mathematics skills
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Experience of client/server communication coding
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Ability to work with a team of mixed disciplines
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Objective-C
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Java
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JavaScript
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SQL / databases
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Mobile SDKs
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interest in Unity VR
Obviously no graduate will have all of that on day 1, but that's fine. What it tells me is that if I were graduating in the UK this year, I'd expect to be writing gameplay code, I should probably have at least 1 Unity demo, and it should probably demonstrate good object-oriented programming ability. And if I already had any of those other skills, I'd throw them in for good measure. The good news is that you can demonstrate these skills in almost any kind of game, whether it's 2D or 3D, real time or turn-based, quirky or mainstream.