I think is pretty similar to what you want to do, instead of being viewed by above, they're viewed by side...

Yeah, 'Frac4D' is exactly what I had in mind except it's a side view. Thanks for posting.

I think this version of 4D Tetris is better than the other one you linked to above because in the 4D Tris view too much is hidden due to the solidity of objects with 3 or more dimensions. In other words, in any 3D version of Tetris, e.g. Block Out, you can't see everything that is going on because of the solidity of 3D objects (unless there was a 3D version that showed you all 2D slices of the playing field) but even given this 3D Tetris's are generally playable because we are used to dealing with 3D objects and can kind of mentally fill-in or keep track of the hidden places in the play field naturally. In that 4D Tris, however, you are being asked to keep track of hidden areas of the play field due to both the 3rd and the 4th dimension. I think that's too much and just makes the game sort of a curiosity rather than a serious attempt at a 4D game.