Nice work ORCA.
First I need to correct something....it's all about the SINGLE shotty!!! (press 3 to toggle between them).
The original Doom2 download from ORCA was a dos only game. It won't run on XP or later on it's own. That primarily why you need the 2nd download to run it in an emulated form.
If you havn't ever played Doom before

, you'll probably think we're mad!!

. However the jDoom app {also known as Doomsday) lets you configure it to play like a modern fps and does allow some graphical improvements. But you still can't deny that it looks like a dog (unless you did play it all those years ago, and then it looks like 100% ART!)
We play co-op mode. It's just us against the map...
The object of the game is to get to the exit. However, there is a whole load of s%&t in the way.
You can replace all the sprites with 3d models, however that just isn't Doom. However, I would suggest downloading the high rez map textures from the link top link here
http://forums.yaa.dk/viewtopic.php?f=32&t=69. I will talk you through how to load them on ts.