According to sloccount rboom has fewer than three thousand lines over the original source release. When I say I have deleted so much code that I am surprised the thing is still a Doom engine, I am not joking. (Figures for comparison: linuxdoom 36k, rboom 39k, PrBoom 58k)
This wad is not on /idgames but on Doom Wad Station. As the author explains, he likes really huge, massive architecture, and so do I so I downloaded it and took a look. I was not disappointed - this map is ridiculous. It also gives you loads of ammunition, loads of room to run around, and then just throws monsters at you, which is the best thing.
It says it is for ZDoom but it mostly worked in rboom. However it does need jumping and mouselook to get 100% as far as I can see, and even with that there are a few apparently unkillable monsters. Also the health and weapon placement is a bit silly - there's no way you'd ever pick up all those megaspheres, so they are pointless.
In summary, I thought I'd found a gem - quite roughly made, even ugly, yet incredibly fun (a bit like Assaryth) - but it was not to be.