Are you running the DOS games in Windows or do you exit to DOS before running them? For the latter you need an utility to initialize the card that can be found here. How well the card works under pure DOS really depends on your motherboard.

You can also have a look here: http://global.aopen.com/products_download.aspx?auno=1112 and here: http://us.aopen.com/products_download.aspx?auno=1127.

What is your current hardware specifications?
If you have any available ISA slots, then I would recommend an ISA based sound card instead for DOS gaming purposes.

It is Intel 815E/EP chipset. No ISA slots. There is sound in the integrated chipset sound driver, but no sound in DOS games.

Ouch, not the best chipset for your sound card when gaming in DOS. The DOS utility I linked to contains a TSR that make the card work, but it got not the best game compatibility. Remember to add HIMEM.SYS and EMM386.EXE to your CONFIG.SYS or the TSR will refuse to work. What spesific motheboard do you have?

Intel 815E/EP, has sound in Doom, but no music in it. That is the chip settings sound.