Hi, i'm new here so hello everybody

I have an old gamepad with terrible buttons, i'd like to reuse the PCB inside to connect it to a joystick kit (like the ones you can find everywhere on amazon etc). It seemed like a simple task until i looked at the PCB:

On the right are the game buttons, they're wired as expected: each two contacts are GND and a button specific pin. They even offer pads to access the traces and solder a wire

On the left is the joystick connection. I expected the same thing as for the buttons, but it's not. They're connected to each other in the following way, which i reconstructed looking at traces and with a tester:

The blue connection is ground, the others are all pin specific. Looks like the yellow goes throu a 1k resistor, the rest of the pins go straight to the IC.
So is this thing common? I've not much experience but i've always seen each pin paired with GND. How does it works exacly?
And most importantly: if i have a joystick like
this one, with a 5 pin connector, am i still able to wire it to the pcb somehow ?
Thanks in advance!