The only way to resolve this is to buy a sound-card to install into your system. To find a sound-card with a game port, follow my instructions below.

First, visit this website. Next, navigate to Computer Hardware>Input Devices. Next, look on the left of the page for the Input Devices menu. You will see a category labeled, "Sound Cards" click that link. Next up we will look on the left again, except this time we will click on a link towards the top of the list labeled, "Advanced Search." Now look down and find the category listing, "MIDI/Joystick." Open the drop-down menu of that category and select, "Yes." Now click the, "Search" button located towards the top of the page.

Before you start looking at sound cards, let's narrow down the choices to sound-cards your computer can use. To do this, we once again look to the menu on the left. This time we select, "Guided Search" located at the top of the menu. Now look for the, "Interface" section of the menu. Here you will click, "PCI." (NOT PCI Express!)

Now you have a list of sound cards which fit your system and at the same time provide you with a game port. A word of advice, look carefully at your choice to ensure that it has a visible game-port. There are pictures of each product, and if you can't tell if it has a game-port, don't buy it. Another hint, don't buy cheap sound-cards, as they are flimsy and break easily. $50+ tend to be better sound cards.

Let me know if this solves your question or if I need to give you other options/explain some points in more detail. If you do decide to buy a sound card, let me know. I'll give you instructions on how to install it.