This is a rather odd ball set.
Two absolutely gigantic levels with many different environments that you progress through, huge spaces to explore, lots of enemies, alternate paths and bosses.
On the one hand it's a litle weerd to go from the t3 first factory stage into an alien cave, ---- on the other the huge amounts of environments insure that you don't get tired of looking at the same background constantly.
With many secrets and alternate paths, this is deffinately one for exploration fans, and as the title says the levels are pretty huge!
My only real problem with this set is the difficulty. With the abrupt change of environments, you can go from a corridor full of enemies that line up ready to be shot, streight into an alien cave where you are riding moving platforms over spikes while acid drops on you from above, ---- which can make things feel somewhat disjointed.
All the same, deffinately a worthwhile set for people who like exploring.