The last full level is TI is, as was the first, a high-tech level. It's extremely complicated, sometimes overwhelmingly so, but it's fun to run through.
This level, like the last 3 spaceship levels, has a ton of windows through which one can see parts of the level that have been passed or not yet reached. Most of the detailing is done in the area surrounding the gigantic slime tank with the three pillars, with complex control panels and lighting effects. One neat trick is the "slime indicator" that activates when the tank is drained.
The path through this level is, as above, quite complicated. You'll be circling the computer core several times and visiting most of the level's rooms more than once, and from different angles. There are small puzzles (jump across the platforms you just raised) and large puzzles (figure out how to get back to the air duct you just unblocked), but few of them involve excessive backtracking or searching for doors. Some of them are ideas I'd never seen before, like the place where you have to edge out onto a tiny ledge to reach a switch on a pillar. The monsters around here are quite powerful, I died again on this level.
Deactivating and reactivating the computer core is a neat trick, and quite a complicated process to implement in a map. I noticed on this run a small problem, which is that the terminals briefly switch to their "finished" state before the lights fade out after the last of the first group of switches is pushed. This is a side effect of the way light-controlled terminals and switches are implemented in the game- they only depend on the value of the light intensity, not whether it is in the "enabled" or "disabled" state.
