Among GURPS books, there are a few that come up time and again as being problematic. GURPS Ultra-Tech is one such book, and as the name suggests, it's a catalog of speculative advanced technology, ranging from conservative advancements on existing technology at Technology Level 9 (TL9) to miraculous technologies requiring a whole new understanding of physics at TL12. Sprinkled among these are the superscience technologies which, while existing at specific TLs, are almost certainly impossible given what we know about the universe. Still, they show up in many science fiction works, and so make an appearance here.
Some of the flak that Ultra-Tech receives is deserved. It was released early in GURPS 4e's life cycle, at a time when Steve Jackson Games was trying to keep up with their promise to release one hard cover book a month. As a result of this rushed schedule, it never received the editing it needed, and there are minor issues throughout as a result. It also lacks the refinements that later books would introduce, like Cost Factors for easily calculating the effect of various modifications on price.
However, the main controversy is over balance, like how lasers stack up against gauss weapons, how the weapons fare against different armor types, and, well...it's mostly about how the combat element stack up against each other. Such is the nature of RPGs, where resolving problems with force is a favorite strategy. Less commonly discussed are the lack of discussion on how the various technologies would affect a society, why the prices don't make sense, and so on.
The core of this problem is very simple: Ultra-Tech is about speculative technology, not settings based on those technologies. Unfortunately, the book explicitly states that its default assumption is that all of the technologies at a given technology level coexist, and so people expect that it will all work together nicely. This is a fundamentally flawed assumption, for two main reasons. One, the authors of a catalog of speculative technology cannot possibly take into account all the implications and ramifications of those technologies, because there's simply not enough space.
The second is more insidious: there is no Ultra-Tech setting. The book hints at four, one for each tech level, and could become many, many more depending on which superscience technologies are included. Beyond that, there are many, many settings in literature, film, and roleplaying games that feature advanced technology, each of which has its own distinct assumptions. Some people might want to play in the near-future world of cyberpunk, others the highly advanced but still familiar world of Star Wars and space opera, and still others want to delve into radical transhumanism.
GURPS Ultra-Tech makes a token effort at supporting this diversity by giving a few brief entries on how to pick appropriate technologies for each. This is nowhere near enough, since it offers little to no advice on how to tailor availability, pricing, stats, and other information to suit the setting. Instead, each item is given but one set of statistics, presented as it were the definitive answer for all possible worlds.
But if taking Ultra-Tech as as if it represented one cohesive setting is the wrong approach, how should one use this book? Use it as a baseline. After you've decided on what you want your setting to look like, pick the TL that best fits your setting, then discard anything that isn't appropriate, tweak anything that remains, and add in technologies from other TLs until you have the results you like.
For one example of how to do this, take a look at Mailanka's Psi-Wars series, starting at this post.
What if space opera isn't your thing? Fear not, in the coming weeks I'll take you through my own efforts to build a setting. The basic concept right now is a star-faring society, with influences taken from Shadowrun and Dragonstar.
And if that's still not your thing? Well, I highly encourage you to write your own! GURPS Ultra-Tech is an excellent source of ideas to build off of, and the more examples of how to use it we have, the better.