None of this is that important to the overall game, though. You can turn Tetris into a turn-based puzzle game where you have an unlimited amount of time to place each next piece, it just has to obey the same rules as having overhead clearance on it, and it's still the same game. This is effectively the game that AI players are playing anyway, since they think faster than the pieces fall and thus time is not a constraint for them.

I agree, I'm just clarifying what was meant by

> Board size - gravity rules - scoring etc. are arbitrary

So 'gravity rules' refer to falling speed, which is unimportant and doesn't fundamentally change the game, same with board size.

But do pieces accelerate AS they fall?

>They move faster at higher levels

Which proves it's not gravity -- gravity would move the same speed always (assuming a vacuum game stage), or would move proportionally to air resistance (so based on shape), etc.

There is gravity, but Tetris pieces are dropped from very high, and have achieved terminal velocity by the time they reach your board.

I know we're firmly into joke territory at this point, but anyway, if that were true, then line pieces would fall faster when oriented vertically than horizontally.

Clearly the real answer is that Tetris is played in a weightless vacuum, and that pieces are shot at a constant speed from somewhere offscreen.

>Clearly the real answer is that Tetris is played in a weightless vacuum, and that pieces are shot at a constant speed from somewhere offscreen.

Obviously not, since the speed increases as the game progresses (of course the planet could have increased its mass in the meantime).

The speed the pieces are fired at is constant within each round, and then increases between rounds.

Obviously the tetrominoes are being fired by a variable speed railgun and the current is being increased with each round.

Right, but this is called 'gravity' in the game, so I think it's what ggp was talking about