In strategy/simulation games there are often tech/research trees which allow players research new abilities/options, improve existing options and decease negative effects.
Some games seem to follow the abc approach of
item 1 -> item 2 -> item 3 with minor stat changes while others make every unlocked option wildly change the way a game is played by throwing new units into the game which are able to change the balance of the game. Some make unlocking one branch block off another for the rest of the game while other will let you research everything. Some let you research multiple things while others will penalize you for switching research before it is complete. On that note tech trees can be progressive (with dedicated research over time unlocking an item) while some need you to collect enough money/points in order to unlock instantly.
What are some general guidelines for when to employ what strategy in a game? What games types of games would benefit more from one tech tree type over another and why? When should a linear tech tree be employed over a branching one?
For example a game where the main character has to build up an organisation and research technologies in secret while others are finding them and shut them down resulting in lost research laboratories, which reduce research output. The research output should increase somewhat exponentially as the game goes on as better technology is unlocked and research laboratories are upgraded. There would presumably be a very large tech tree to explore and the constant danger of losing facilities to other parties until you either unlock some endgame tech or lose everything.
Why this isn't a duplicate
Some people are marking this question as a duplicate because there is a related question about tech tree size. This question has to do more with the connections, cost and relationships between the technology options (of which size is a factor but not everything).