It's quite the tall order, but limiting it to just the two players -might- simplify it. I'm not sure.
I think the way to tackle this will be to make a single-player Tertis game, then start looking at how to rig up everything with RPC so that two players play tetris side-by-side. After that works, then look at the inter-player interactions, like dumping garbage blocks.
My rule of thumb for networking is that complexity becomes an exponential curve, so just be ready to tackle that.