An interesting feature of NetRunner is that each player uses completely different cards and has different abilities, yet the game is still balanced. This is in contrast to most other CCG (collectible card games), which depict a "battle between peers", where each player has the same abilities and draws their cards from the same set.
The Corp builds data fortresses, defended by "ICE" software, which the Runner must bypass in order to access the contents of the fortress. For beginners, experience has shown it is quite difficult to win as the Runner - the methods for keeping the Corp at bay are not immediately obvious and require some practice. This may have contributed to the demise of the game, with new players being discouraged at always losing when they played the Runner.
The game, unfortunately, did not sell well enough to last more than a few years in production. One complete expansion, Proteus, was released and also a smaller set called "Netrunner Classic" with 52 new cards was released in November 1999. There are around 520 NetRunner cards, almost all of which are allowed in tournament play.
Zvi Mowshowitz, a well known Magic: The Gathering Pro-Tour player, tried to buy the license for NetRunner from Wizards of the Coast. He set up a Yahoo! Groups group called NetRunner R&D which spent many months debating how to tweak the game by banning/altering certain cards etc. in the event of its re-release. Sadly the deal was never completed and the game is no longer produced.
The gatlingEngine, being developed by www.ccgworkshop is making NetRunner available to play online, for free.
Cards may still be found on eBay and other online auction sites. As with many other niche products, a small but loyal group continues to play and promote NetRunner.