The game may be old but the atmosphere and story brings a psychological horror aspect to it since you can see what your protagonist is thinking through the loading screens between levels which give you text written like a journal including dates setting the game in the year 1997 and compared to the other postal games this one is more dark and creepy having no music during gameplay, all you can hear is screas from people you kill
thank god GOG made this game free for a while so people can experience it, it's basically an action adventure game, with a quite good open world (keep in mind that this is the original game optimized for newer pc's but it gives you the og one as a bonus so the map is not that detailed) but the thing I love the most is the atmosphere so yeah if you want a scifi action adventure open world classic this is the game for you