I quite like Fantasy Flight Games' Twilight Imperium, 3rd edition. It's not perfect though. The rules for the base game include possibly the worst tech tree in existence. The Shattered Empire rules maintain the same style with the same problems, while actually making them worse by trying to shoehorn the new technologies into a structure not intended to support them. Fantasy Flight has given up completely with the Shards of the Throne rules which don't include a tech tree at all.
BoardGameGeek users have submitted a wide variety of alternative trees in the game's file upload area, trying to address some of these problems. Unfortunately, the basic approach seems to be fixing Fantasy Flight's tree, rather than starting from scratch to present the tree in the best possible way. A list of goals proceeding from first principles would be helpful. Ideally, a tech tree would
- keep related techs together,
- generally flow from techs with no prerequisites to techs with many,
- avoid unnecessary line crossings and other visual distractions,
- clearly distinguish between needing to satisfy all prerequisites or just needing to meet one,
- remain compact with short unambiguous connections between technologies.
Clearly, not all these goals can be satisfied simultaneously. I want a tech tree that is useful for answering the question: "This tech is pretty cool; what do I need to get that?" These tech trees forego a left-to-right progression in terms of the number of prerequisite technologies, in favor of short clear non-crossing lines illustrating the relationship between technologies. Multiple arrows pointing to a technology indicate a logical OR: at least one of the prerequisites must be satisfied to unlock the given technology. Multiple lines which join into a single arrow at a particular technology indicate a logical AND: all of the prerequisites must be satisfied.
It's axiomatic that one can't please all the people all of the time, so I'm trying to please ⅛ of the people all the time, with eight different tech trees. There are shaded and outline-only tech trees, a titles-only version that fits on half an 8½ x 11 inch page and a full-page version that includes descriptions of each technology, either with or without badges indicating which technologies come from which of the two expansions.