Before I forget, I attached a save at the start of the mission in case you need it for something. I will just call the aliens "aliens" because I know people look at the spoilers anyway.
The first thing you notice is that you can walk off the front back and sides of the ship. That's fine for the player because he will figure out right away not to do that, or he can go explore the outside of the barge with the aqua-lung or exosuit (which I did bc it was really cool).
The problem is that the aliens can walk off the edge, too. IDK why the hell they would, but one did when I played. In save 101 you can see him at the top rear deck of the barge, thinking about jumping, and I saved right before he does it. Save 102 is another save some time later just after I found him. Also save 102 is a good chance to see if you think the exosuit might be a bit overpowered, because I had one instance where I took 3 shots from that alien with no damage. Could just be luck, though.
A similar issue can be found in save 201. There you will see a (large) alien that has wandered completely away from the action. I chased him all over the place because I didn't think to use debug mode until really later on (like turn 70).
In save 301, I have a large alien basically pinned down at that elevator. He wants to come up and attack, but if I don't move, he can't come up. This exploit existed in vanilla, too, so I guess it's not a bug, but it can also cause inconvenience. I can't free up that path without losing someone or doing something exploitative. Just something to think about. I think everybody knows about this issue with TFTD.
Save 401 is not a bug. It shows a person called "Yehide" towards the lower back of the barge. I am asking you to consider putting a small/narrow door there to link that back corner room with the largest room. Otherwise there's just a big dead end there which was kind of annoying. It's just a minor request, though. I really think the level is beautifully done.
The last save, save 501, is for you to have so you can review the end of mission stats. Just shoot a torpedo at the central elevator with Lielit to kill the last large alien (who is "stuck" there again). In the mission stats, you can see that there are so many unique items to list that the list runs into the buttons. It looks to me that if you were to remove three unique loot items, then the whole list (including the total) should probably fit correctly on the page. If I may suggest: take out Alien Reanimation Zone (since there are only 2, and maybe it doesn't make sense on the barge anyway), and for the other two, I don't know (but maybe alien sub construction (since it's a barge, not a sub), and alien cloning (since it's not a base)). It's up to you. I guess it depends also one what objects you show in the barge.
This last one makes me feel kinda stupid, but I find that the large torpedo and heavy torpedo sprites are somewhat difficult to tell apart at a glance. Could the heavy torpedoes get a blue ring or something, since the Advanced Torpedo launcher has noticeably wider blue rings at each end?