UT GOTY launch failed, Steam Windows 7

When I launch steam then go and try launching Unreal Tournament '99 it just doesn’t launch. The loading timer on the mouse appears for a few seconds then disappears. I waited a while but since UT didn’t launch I clicked again and then it gave an error message stating application already running (5388). On the Steam menu I can see the “X” STOP symbol on UT instead of PLAY.

However, UT still didn’t launch. This keeps occurring despite multiple tries.

I tried exiting steam and restarted the PC but still no luck. I even verified the integrity of game files, everything was fine but UT doesn’t launch.

A few months ago, i.e. when I last played it was working smoothly. I don’t know what changed. I haven’t installed any new software or made modifications to my PC since.