My list of cyberpunk games has been up for a while. But although they appeal to tech-heads because of their technological theme, most of these games actually have little to do with real-world technology because they take place in a fictional world where technology is simplified to fit in with a storyline better. Cyberspace is a world of conceptual icons laid over a big grid, computer usage is dumbed-down, and most of the game focuses on plot rather than the technical aspect of things. This can be fun, but serious computer techs probably crave a more realistic gaming experience.
Well, if you thought good cyberpunk games were hard to find, good engineering/scientific games are on a whole other level. While cyberpunk games are forced to bridge the gap between technology and game in order to have lasting appeal to general audiences, a really technical game simply can't appeal to the general public at all. Very few people are interested in a game that feels more like a university class than anything. It takes a special kind of person to like that kind of game. It takes a real math geek, someone who appreciates the love of complexity.
The result, of course, is that there are almost zero of these kinds of games on the commercial market. You probably won't see them on the shelf at your local software store. However, this isn't such a bad thing when you think about it, because it means that the technical games which DO exist are mostly freeware, available for anyone to download from a website. Free games, which challenge your mind the way the computer geek in you wants it!
I should mention that only relatively well-known games are listed here. As such, many of them are in fact commercial games, although most of those are so old that the companies which made them have long since gone out of business. Because it focuses just on major titles, this list is quite short. A much more complete list, complete with a ton of links, is available at http://tpga.virtualave.net/game-links.htm.
One of the most important games in computer engineering circles ever made, Core Wars was the game that founded the idea of making software "robots" and letting them battle each other to the death in a simulated arena. You write robots in a language similar to assembly language, then put them in a simulated memory space, where they struggle to make each other crash with some kind of error, or simply to eliminate each other by claiming all the memory cells for their own. Core Wars has inspired many, many knockoffs.
One of the better-known Core Wars knockoffs, C-Robots is simply Core Wars with the robots written in C instead of assembler. Originally written by Tom Poindexter, who still makes the game available for download at his homepage at http://www.nyx.net/~tpoindex/.
A company called ETCAI Products makes a line of excellent games which simulate electronics. Among their products are Meter Challenge (which simulates using an ohmmeter or a voltmeter to troubleshoot a circuit), Digital Challenge (which simulates digital electronics), Power Supply Challenge (take a guess), and more. These programs make a fun and interesting way to learn electronics through puzzle-solving activities.
Hailed by some as "the next Robot Odyssey", MindRover is a stunning experience which has been tragically ignored by the mainstream gaming industry, although it has had a decent amount of attention in the underground/shareware gaming communities. Essentially, the goal of MindRover is to build a robot. Your robot(s) will be called upon to engage in various challenges with computer-controlled robots. Your robot may have to win a race, capture the opponent's flag in a capture-the-flag type challenge, or simply engage in a head-to-head deathmatch. MindRover allows a tremendous amount of freedom in building and programming your robots, making it a highly fascinating and brain-stimulating experience. It's basically the next generation of Robot Odyssey or Omega. You can get more info from Cognitoy's homepage.
One of very few commercially-released games on this page, Omega is a sort of Core Wars in BASIC. Tasked as a research scientist, your job is to design tanks which are artificially intelligent, and send them out onto a simulated battlefield to test them. The game is a great introduction to programming. It was released many years ago by the legendary Origin, the same Origin that made Wing Commander and Ultima.
It seems hard to believe that this game was released by The Learning Company, a company best known for its child-oriented, educational software. What's even harder to believe, however, is that this game is child-oriented too. It seems a little ridiculous, because the truth is that any adult would find it as challenging as any puzzle game out there. Clearly, it was targeted at older children, and not very young ones. Age targeting aside, however, Robot Odyssey is simply one of the best educational games ever released. It teaches basic electronic theory by making you build circuits inside robots. It will take you a long time to finish the game, but if you enjoy engineering games, you'll enjoy this.
Essentially, Robocode is a Java Corewars.