There are some nice 10+ year old DOS and Windows-games which you might be able to play very well. But I don't think you mean those. So better tell us a few names of the games. And your OS.

For current games a not too old version of DirectX (for video and sound) should be present and working. So run dxdiag (from start/run) and note the version of DirectX on tab 1 (bottom line). Then run all diagnostics from the other tabs. Post the results if necessary.

Also check of other parts of the system are up to the requirements of the specific games.

Just a question: how do java and flash games work?