D1: Overall, I think this was my favorite section. It felt like a D1 level, and I have always preferred D1 single player over the others. The size of the map felt overwhelming at times. Despite spending hours in there, I never felt like I knew where I was. It was dark, and atmospheric. My only problem with this section was how easy it was to run into a large group of robots that were more advanced than the weapons I was carrying. Granted, the pacing of one level can't quite be the same as the original mines. That was ok though, because the other parts are started with almost everything on board.
D2: This section was by far the most complex and frustrating. Much more time was spent trying to find where to go. I liked the idea behind getting the red key. Very clever. I have to admit though, that I couldn't find the right way to go to get to one of the panels
. I used a guided missile 
. Then I got the key, and worked my way backward from a previously locked door that led to the area. When I found out how I was supposed to get there, I was a little surprised about how easy it would have been if I had just looked a little harder. The reactor room was devious.D3: This was probably the biggest surprise of the whole level. I didn't realize that D2X-XL was so capable of making something look like D3. Frankly, it looked amazing. I was also surprised to see actual D3 bots there. Sure they didn't behave quite the same, or sound the same (at least on my computer... are they supposed to sound like D3 bots?), but they looked right. At least most of them did. Some still looked like D2 bots. My only problems with the D3 section was it's length, and the final boss. After spending hours in the D1 and D2 sections, I was expecting a similar amount of time in the D3 section. I'm not even sure it took me 20 minutes. The final boss, for whatever reason, was completely invisible for me. The targeting reticle would let me know where he was, but I couldn't see him. I'm wondering if a model didn't load properly or something. Anyway, that made him much harder than he would have been otherwise. Also, I wasn't expecting him to be the end, so I didn't use any of my missiles on him. I had 4 earthshakers too.
Overall: An amazing tribute to the Descent series. Even though I got lost, confused and frustrated, I enjoyed going through it. I think it would be fun to go through it on co-op, but only if multiplayer games can be saved. I don't think I could do it in one sitting.
Not to mention there would be a lot of "where are you?" "No idea, you?" It would be pretty fun. Thank you Sirius. Nicely done.
The flat room with the coloured pillars, there was an exit between a couple of them that you didn't see? That ... may have been intentional 
