
It is highly recommended that you hold off the completion of the interrogation untilĪll the prerequisites have been researched. So, as a rule of thumb, if an alien is a prerequisite for any particular tech item, In order to get D to appear, you must capture another alien and interrogate it again. If you were to interrogate alien C before completing research on A and B, technology D will not appear for research once you've completed research on A and B.

The word 'prerequisite' is used quite frequently There are many documents in a variety of formats describing the complete research tree on the Internet that you can peruse. This guide should help to assist and point out some of the stickier bits.Īlso note that this is not a reproduction of the research tree. Unfortunately, as the research order in TFTD is non-linear, that is to say you can research anything you've got in any order you want, a lot of us are less fortunate. Some players may have had the luck of not bumping into any of these errors by picking all the right research at the right time, or have a game that doesn't seem to have these problems.

They have succeeded in doing this, but have also introduced many glaringly unacceptable errors in the process that can prevent you from completing the game. The designers of X-Com Terror From The Deep seem to have attempted to make the research process in TFTD much more complicated than its very straightforward predecessor's research tree.
