I want to make Tetris with C#. There are a few choices I could make. I could use regular Windows graphics or maybe CocosSharp. I know how to program (business), but wanted to try the other. I'm familiar with the gameloop kind of thinking, OOP and all the rest. Just wondered what you thought I should use. Last time I thought about this it was the GDI library. Thanks.

Second that, monogame is nice and portable to android and iphone. I believe after ms aquired xamarin xna is sort of back under a new name. X-platform tools are now free too, they were not before. You can overlay the native ui if u don't fancy building a ui framework.

What is X-platform tools?

SFML .NET bindings

http://www.sfml-dev.org/download/bindings.php

MonoGame and XNA.

Xna is a fine choice, the 2d api is really simple. Though the library is kind of dead.

Second that, monogame is nice and portable to android and iphone. I believe after ms aquired xamarin xna is sort of back under a new name. X-platform tools are now free too, they were not before. You can overlay the native ui if u don't fancy building a ui framework.

What is X-platform tools?

i just mean cross platform tool. These are the tools that compile your project to run on android and iphone. There are also good android emulators.

The first game I made was a pong in winforms (I knew no better). So you want to tackle some engine related problems too?

It doesn't matter really. But since you want to start in game development why not choose an engine like unity? It's overkill for a simple tetris clone but you gain valuable experience in it's component system, true OOP is something from another decade in component systems lies the future.