user87089: On day to day basis I'm more of a high level programmer, with little electronics knowledge, apologies in advance if I lack some nomenclature or basics. I communicate with my Arduino Mega via firmata, so won't really bother with code as I believe my issue is 100% hardware issue (if proven wrong I'll share details surely)
I'm creating a 'keyboard' with 60 arcade style push buttons (2pin), and I distinguish them by different resistance when circuit closes with A0-A9 (10 analog pins, 6 buttons each), and I need the rest of the pins for other functionalities.
I've created a circuit similar to this fritzting schema:

So my issue is: when press button A0/button 1, pins A1 & A2 also read the same value. If I press A0/button 2, I get a different value and can determine which button in A0 was pressed, but again - A1 & A2 also read this, even though I didn't press them.
I suspect I might've taken a different approach or even out of the box "keyboard" chips, but this is the route I've taken.

How do I make it so when I press A0/button 1, A1/A2 doesn't read the value? Do I need separate V5? Or I simply need to put the wires differently somehow?
Update: as per chrisl comment
I've updated the circuit by adding a resistor for each button group:

And that has solved my issue.

user42015: Of course all three analog inputs show the same value. You have literally connected them to each other. Each green wire is connected to a red wire, which leads to the resistor at the bottom. Thus all three inputs are tied together.
You can fix this by using one bottom resistor for each group of 2 buttons, each connected between 5V and the analog input/button system.
And when using analog inputs for multiple buttons the binary resistor latter is an interesting concept, which might give you more buttons per analog input (depending on the noise in your environment). Though the typical way to read so many buttons would be using an additional chip/microcontroller to scan the buttons in a matrix style arrangement. With your current circuit you still need 30 analog inputs.

87089: <p>On day to day basis I'm more of a high level programmer, with little electronics knowledge, apologies in advance if I lack some nomenclature or basics. I communicate with my Arduino Mega via firmata, so won't really bother with code as I believe my issue is 100% hardware issue (if proven wrong I'll share details surely)</p>
<p>I'm creating a 'keyboard' with 60 arcade style push buttons (2pin), and I distinguish them by different resistance when circuit closes with A0-A9 (10 analog pins, 6 buttons each), and I need the rest of the pins for other functionalities.</p>
<p>I've created a circuit similar to this fritzting schema:
<a href="https://i.stack.imgur.com/2p9W2.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/2p9W2.jpg" alt="enter image description here" /></a></p>
<p>So my issue is: when press button A0/button 1, pins A1 &amp; A2 also read the same value. If I press A0/button 2, I get a different value and can determine which button in A0 was pressed, but again - A1 &amp; A2 also read this, even though I didn't press them.</p>
<p>I suspect I might've taken a different approach or even out of the box &quot;keyboard&quot; chips, but this is the route I've taken.</p>
<p><a href="https://i.stack.imgur.com/5i4SO.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/5i4SO.jpg" alt="enter image description here" /></a></p>
<p>How do I make it so when I press A0/button 1, A1/A2 doesn't read the value? Do I need separate V5? Or I simply need to put the wires differently somehow?</p>
<p>Update: as per <strong>chrisl</strong> comment</p>
<p>I've updated the circuit by adding a resistor for each button group:</p>
<p><a href="https://i.stack.imgur.com/iYPke.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/iYPke.jpg" alt="enter image description here" /></a></p>
<p>And that has solved my issue.</p>
 42015: <p>Of course all three analog inputs show the same value. You have literally connected them to each other. Each green wire is connected to a red wire, which leads to the resistor at the bottom. Thus all three inputs are tied together.</p>
<p>You can fix this by using one bottom resistor for each group of 2 buttons, each connected between 5V and the analog input/button system.</p>
<p>And when using analog inputs for multiple buttons the binary resistor latter is an interesting concept, which might give you more buttons per analog input (depending on the noise in your environment). Though the typical way to read so many buttons would be using an additional chip/microcontroller to scan the buttons in a matrix style arrangement. With your current circuit you still need 30 analog inputs.</p>
