Look at the release date, it is not the full source.
Unreal 1 was an awsome game, though the Return To Na Pali expansion pack blew it away! If Unreal 1 was too slow paced for you, then try the expansion pack.
Personally I LOVE both and I can not deny that the game TOTALLY revolutionized the way FPS look and play today, a highly underated title.
Now apparently it is possible to play Unreal and Na Pali under UT, read this converation here and check out the links:
http://www.dcemulation.com/phpBB/viewtopic.php?t=43682As for Dues Ex 2. I've never played part 1, but will be doing so VERy soon. I can say that part 2 (which I just completed last night) was VERY entertaining, it is like a cross between Knights Of The Old Repblic and Half-Life if you can imagine that. Also with this engine you get a small idea of how DOOM3 will be handling light, and how Half-Life 2 will let you interact with objects.
If you like hard core Cyber Punk fiction, and are a RPG/FPS fan then I would highly suggest this one. it may be VERY VERY confusing for a long while, but it is supposed to be, as the game goes on, the plot becomes more clear. HIT YOUR RENTAL STORE AND RIP IT!! Infact this one is worth paying for to be fully honest!

<