Recently I've finally got around to learning how to do a 4-wide combo. I figured since I was thinking about these ideas anyway, I may as well leave them here for other players, who are also new to the 4-wide, to read. The first thing I want to point out is this guide,
and more specifically, this picture.
So, what I've been trying to do is simplify this as much as possible... to come up with "rules of thumb" to follow. The first thing you may notice about the site I mentioned in the above paragraph is that for any case, the I-tetromino has a maximum of two solutions and always at least one (the horizontal orientation). The O has 0-1 solutions per case. The zigzags (Z and S) and T have 0-2 solutions per case, and the guns (L and J) have 0-3 possible solutions per case.
I find it useful to be familiar with the cases that may look like a continuation at first, but they will actually lead to a dead end. It's good to sort of logically deduce what options you have left by looking ahead at what sequences will lead to deadends and crossing them out, so to speak. Then, you have a smaller list of candidates for sequences of placements that may actually continue the combo.
You have to remember that the hold feature effectively gives you two active pieces at any one point. Say you have an active piece J and your held piece is a Z. Well then, technically you can use either of them right now. At any point in the game, you have two pieces at your disposal (unless you've used hold already on the current piece or the active piece and hold piece are the same). So then, if one of those two pieces will lead to a deadend, then you know right away that you'll need to use the other piece. If you have more than one option for said piece, and one option leads to a dead end and the other doesn't, then you've just figured out how you need to place that piece (the only option that won't lead to a dead end). Often, we'll only have one option, and it's easy to decide where to go. However, it is very important to recognize cases where both your hold and active pieces will work or when you have multiple options with one or both pieces that will work. These are the times you need to look ahead in the queue and figure out which ones will lead to deadends further down the road.Dead ends
Try to avoid the following cases (unless you plan on ending the combo soon anyway).
Since an I can solve any case, they're the best ones to hold, all other things being equal. The only other thing worth noting is the vertical solutions.
This solution is useful when you run into these traps where you don't get an O tetromino soon enough:
Instead, use this:
Zigzags and O's
The pieces I find myself "deadending" on the most are the zigzags and O's (especially when they're close together in the queue). That's why I find it useful to identify them in the next queue and work out a plan before they come up.
This particular case can cause problems. You need either an O or the correct gun (L or J) to go along with it.
So try to avoid creating it if you see you don't have an O or the corresponding gun:
Instead, create a different, more welcoming formation:
This can end your combo:
So do this instead:
And instead of this:
This shape is usually very welcoming:
...but it can cause problems when zigzags are coming:
In this situation, this would work better:
T's and Guns
Don't create this shape unless you have either a T or the corresponding zigzag or gun:
It causes deadend piece combinations.
You might do this instead:
As I mentioned before, the flat 3-in-a-row case usually is pretty flexible, but you still have to pay attention:
You can allow for those pieces by using the vertical I-tetromino instead:
Those are just a few "for instances" that I found useful. After enough practice, you begin to get a feel for what will work and what won't. Combo prep stacking
There must always be three "minos" in the 4-wide well--not 0, 1, or 2. To do this, you put 3/4ths of a piece in the 4-wide area from the start. I prefer to use a zigzag, but there're pros and cons of each opening, I guess.
There are many possible combinations available to us when building or 3-wide side stacks. These are just some examples:
With regards to the 3-wide stacks, we need to pay special attention to T's. In short, if we put a T on one side, then we need to stick the next T on that same side. T's change the dynamic of the stack and make it harder to deal with. So instead of "T-ifying" both the left and right stacks simultaneously, it's best to instead T-ify one stack and then use the next T to un-T-ify it. Why are T's special like this? Maybe it's because they have a strange property that differentiates it from the other pieces. If you put all the tetrominoes on a checkerboard, you'll find that they all have two dark "minos" and two light colored ones... that is, except for the T.
Fill it in later
Sometimes we'll find it necessary to leave vacant spaces in the stack and fill them in later.
If we can't place a piece in the 3-wide stack without it causing an extremely unstable stack and/or hole, then it's usually best to just toss it in the 4-wide stack until the 3-wides stabilize. Make sure you drop it in a way that doesn't lead to a deadend. Also, try to resort to this as little as possible.
That's all for now. Good luck! By the way, I'd be happy to add any examples that you guys come up with to this post later on if you like.
is the orginal link. I used the imgur one above, so as to save the host a little bandwidth.