Connect-4. So simple - a 6 row, 7 column grid with gravity, two players taking alternate turns at putting a red or yellow piece in until a row, column, or diagonal of one colour and of length four is constructed. In fact its simplicity, combined with the garishly bright red, yellow and blue colour scheme, and possibly also the 7-14 age tag, have caused many to consider it a game for kids. Not something for us real, adult people to condescend to play.

Well, it is my opinion that those people are wrong. Connect-4 is one of the most challenging, interesting and above all deep games ever invented. Like draughts/checkers, although it has been shown by computer that the yellow (first) player can always win, not even the best players in the world can guarantee a win. The possibilities for play are not endless, but they are so huge in number that the best that can be hoped for is to understand the openings, and to develop strategies for play. I'm going to talk about them now, so this is your official Spoiler Warning.

First, the openings. Yellow (who plays first) should always take the centre circle. If she doesn't, red can theoretically always win, and indeed generally does. Now it is generally accepted that red's response to this should not be to go on top of yellow, as yellow can then top the tower and get the crucial (4,3) circle, which can become an axis for diagonals and a horizontal. Personally I prefer to go just next to yellow - (5,1) or (3,1) in co-ordinate notation. After this, I don't believe there are any accepted rules for the progression, and many classic openings are possible, though I won't go into them here.

Strategy. Most people who play the game for an extended period tend to go theough a steady progression of more and more advanced strategies. First off, they think merely about trying to build loads of lines, in the hope one will be connect-4able. This soon yields to the first major strategy, or rather tactic (being local/small-scale) - using the "forced move". This is where you form two connect-3's simultaneously, with either both toppable to a connect-4 immediately, or with the "active site" (that is, the circle the taking of which would lead to a connect-4) of one being directly above the other. So your opponent will be forced to occupy one circle, allowing you to take the other and hence win. Cool! But as players become more experienced, they quickly learn to look out for this simple ploy, and such forced move tactics must become increasingly more intricate if your opponent is to suspect nothing until too late.

However, beyond a certain point of skill and foresight, these tactics become irrelevant as they are always seen and stopped. Here a new element of the game comes into play - Zugzwanging. Now that's a chess term, but it is just as applicable here, and it refers to a situation where the onus to move is a problem - i.e. when all legal moves for a player lead to them losing as a result of making that move. This happens in connect-4 because the board is finite. There are only 42 circles, and each column can take only 6 pieces before it is filled. So soon enough only a few moves will be allowed, and we frequently see the players being forced just to take turns filling up the columns until a connect-4 is formed (or the board is filled, which means a draw, though this is rare). So the trick is to make sure that it will be your piece that connects a four. This is tricky indeed, but you can get a decent chance by understanding one crucial consideration - parity. That is, evens and odds. Each column is 6 circles high - an even number. This means that it makes sense to consider each odd circle as "belonging" to yellow, and each even to red. The exact way this works is a bit complicated, but as a general rule of thumb yellow should aim to get odd active sites, and red even ones - although as it turns out, red also wins if he gets two odd ones.

So at this stage, we see a really interesting game having developed, where each player is constantly having to try to out think the other both tactically - trying to win by forced moves - and strategically - aiming to win by zugzwang - and indeed also trying to tactically achieve strategic ends. It all gets quite complicated, and very entertaining. So much from a clunky blue board and 42 coloured circles...

One final point. Some people think this is a game that can be as well played on pencil and paper as it can on a board. They are wrong. Pencil and paper is fine for practice, for figuring out strategies, or for when you don't have a proper board to hand - but nothing beats the sight, the feel, and above all the sound of letting your blindingly bright yellow circle chute down the column of an actual official moulded plastic Milton Bradley blue board, to hit those three appropriately coloured pieces previously put in place, bouncing with a delicious rattle and settling into yet another victory... pure bliss.