Note: This guide was written before Command Blocks were a thing.
Connect four is a fun game you can play with a friend and it’s easy to build in minecraft.
You could go for a very simple version which requires a lot of manual input or you could build a semi-automatic system whith a reset button, automatic block placement and any other options you may like.
I’m sure most of you have played connect four at least once in your lives and know the rules by heart, but for those who don’t, the rules are as follows: The aim of the game is to make a row of 4 blocks, either horizontally, vertically or diagonally. This is done by dropping a block (sand or gravel) at the top of the playing field, which will cause it to drop all the way down. Once you’ve dropped your first block it’s your opponent’s turn.
Your opponent now has the chance to drop a block where he wants, including on top of your block. You then keep taking turns, but you’ll have to think ahead to make sure you can get a row of 4 blocks before your opponent does. You may also want to block your opponent or set a trap by planning a way in which your opponent will be unable to prevent you from getting a row of 4 blocks and thus connect four.
The game is fairly simple, but it can be quite fun if you have a good opponent.
Building a Basic Minecraft Version
If you’re looking for a basic version, all you will need is a 7×6 playing field (some versions have bigger fields) in which you can drop gravel and sand.
The image below shows such a basic version. The players will have to climb or fly up to the top to drop their blocks, which may be a bit annoying, especially if you can’t fly.
Note that you have to drop 2 blocks each turn, otherwise the next block you drop will not show up. You could make a very basic version which will only require you to drop 1 block, but this will make the field look a bit boring and sometimes confusing.
If you’re looking for a decent reset system, place redstone or other blocks like redstone (torches, pressure plates, etc) under the playing field. When you’re done playing, simply destroy the wool blocks supporting the sand and gravel and let it all fall on the redstone. The redstone will cause the blocks to break and drop as an item, which means all you have to do is pick them up and replace the wool.
Building a More Automated Version
Constantly having to fly up and down between placing the block and checking the field can be a real pain, so we’ll at least want a system which will place the blocks for us.
A system which tells who’s turn it is and a more automated reset system would also be very useful. These are exactly the things I’ve created. The only thing you can’t automate is the refilling of sand and gravel, as no matter how much you place down, you will run out of them sometime, but by using world edit, replacing them will take seconds.
First the automatic block placement system and the turn indicating system, which are both part of the same circuit and the biggest part of our field. We need a system which will push either sand or gravel, depending on which player pushed a button and we need a system which will place the block in the right line.
The line system is quite simple. All you need are 7 circuit lines for each player, which are each connected to a button which represents the position in the playing field. The biggest challenge is hiding the redstone and making sure the circuits don’t get tangled up. This means we’ll mainly use redstone torches and redstone repeaters.
To hide the redstone we first lead the signal underground with a simple system shown in the image below. Unfortunately we cannot place them directly next to each other, as the redstone will connect and power 2 rows at the same time, so we change 3 of the rows by placing them closer to the place the player will stand.
Once the circuit has been lead down, we also need to add a system which will indicate who’s turn it is. This is done by splitting the signal with a redstone torch and leading 1 signal down and 1 signal slightly up, as soon in the image below.
The signal leading down can tangle with all the other signals which have been lead down, but make sure they don’t mix with the signals leading up, or else they’ll cause multiple rows to be powered.
The signal we’ve lead down will connect with a T flip-flop, which will turn off 1 redstone lamp and turn the other on each time any of the buttons are pushed. This is pretty much all there is to the turn indicating system, though you can expand upon it as you see fit.
The signals we’ve lead up are now directed to the other side of the field, where they will be lead upwards to the block placement system Transfering the signal upwards is quite easy, you simply alternate between placing a redstone torch on a block and a block on that redstone torch, as seen in the image below.
However, we’ll need to move the circuits a little, still done with blocks and redstone torches, to make sure they meet up with the right path at the top.
We have a total of 14 possible inputs, which all lead to 1 seperate pair of pistons. The red circuits lead to pistons pushing sand and the blue circuits lead to pistons pushing gravel. This is basically our block placement system. Each time a player pushes a button, the pistons connected to it will push 2 blocks of sand or gravel. The pistons will then retract and the sand or gravel on top will fall down, ready to be pushed by the pistons again.
I only place enough sand and gravel to fill up the whole playing field (12 blocks), which means you’ll have to refill the game after every game, but it also means it’s more compact. You can make the stack as high as you want, to allow multiple games to be played without having to refill the sand and gravel stocks.
All there is left to do now is create an easy reseting system. All you need for this are normal pistons, some redstone, a redstone torch and a lever. The redstone torch will be our inverter, which means the pistons will be powered until you pull the lever. This isn’t really needed, as you could simply pull the lever down to keep the pistons powered and pull it again to reset the field, but I prefer this method.
Place a piston in each of the 7 rows, but make sure they don’t block the sand and gravel. Connect them all with redstone and connect the redstone to the lever (or redstone torch), which will cause the pistons to extend.
The extended arm should be what prevents the sand and gravel from falling down, which means that when we retract the pistons, all the sand and gravel will fall down. By making it fall on redstone, torches or other such blocks, the gravel and sand will be destroyed and dropped as items, ready to be placed back in the game.
This is all there is to this semi-automatic connect four game, which may be a bit of a hassle for those less experienced with redstone circuits, but it shouldn’t be too difficult to do.