The question has been closed Aug 25, 2013 at 06:34 PM by fafase for the following reason:
Question is off-topic or not relevant
Of course you can make a Tetris-style game with Unity. As for where to start, you should probably make your way to some basic programming tutorials, and Unity tutorials. However, if you're familiar with C# or Java Script, you should have no issues with programming, and should just go straight to some Unity tutorials (YouTube and Google are your friends).
Plan out your project carefully, as you would with any programming project, and build up art assets and scripts, as needed. Beyond that, you won't find many people around here willing to give you anything without a more in-depth question.
Basically, here's how this place works: You make some attempts at accomplishing a specific task in Unity, and if you get stuck, or don't know how to accomplish a specific task (and I'll get to how I'm defining specific in a moment), then you come here and ask about it.
The question you've asked here is pretty general, though I let it through, regardless, as I can clearly see you're not simply asking for someone to build the game for you, and I believe you do at least deserve an answer, though it may not be the one you were looking for.
More or less, project planning isn't really something people will give much for on here, in the way of detailed assistance. Good luck, and remember: we'll always be here if you need help, just come to us when you've got a better idea of what you're doing, next time XD
[EDIT] Here's some tutorials you might want to check out:
Also, there's the Unity Manual