Playing games on emulators is usually bound to using arrow keys on the computer keyboard or an analog PC joypad. This ruins all the fun. The right way to do this is of course using a real arcade joystick.
The problem is on how to connect the arcade joystick with USB. Luckily there are controllers that are designed for this job. The most famous is the Jamma USB controller board and they are used for MAME arcade cabinets. You can also buy cheap Chinese board, which are also capable of doing this. I chose this Zero Delay Arcade USB Encoder. It can be bought in Chinese online stores for around 7 US dollars. It comes complete with USB and other connection cables.
You will also need a joystick connector for the board. It is called DB9 male connector and can also be found on the Chinese website mentioned before. If you are lucky you can buy 10 pieces for 1 US dollar.
First we need to connect the cables to the board. I have written a blog about this board before. We are only going to use the connection for directions (up, down, left, right) and 2 of the 12 possible buttons. Atari and Commodore uses only 1 fire button, but the MSX can use 2, so we are going to solder support for the second button.
We are going to use this schematic to connect to the DB9 plug. This is the view from the connector side, so we need to reverse it. Also we are not going to use the +5V pin.
This is how it looks after soldering the wires.
We are all done. Now after connecting the USB cable Windows should recognise the controller board.
I have tested the joystick with Steem, which is an Atari ST emulator. Inside the emulator you can configure the controller.
Now you can play your favourite games like IK+.