Chasm was the last game to use the Doom/Heretic/Hexen engine, it's very enhanced since then. Gurra991, the iD FPS games are actually Open Source. But the registered WAD files are still commercial. This is why we have millions of sourceports out there 

Unfortunately there is no sourceport of this one. I thought there was, but I mixed it up with Strife. Bummer.

@Kamla
All of the doom games aren't abandonware (dunno if any of 'em is) Quake isn't abandonware and nor is Duke Nukem, Sure they are all good but not abandonware  

You have to play this game with Dosbox, otherwise it will stop after the first dialogue. Furthermore, the sound seems to be very weak, might be a problem with dosbox. The game itself is not that bad, but I think there are a few better shooters out there, for example Doom, Quake, Duke Nukem.