The recently-released Prey has been around for longer than most people might expect - almost longer than Duke Nukem Forever. The portal technology had been even more emphasized back in 1997 when the game was shown publicly for the first time. Obviously, besides this mentioned core concept, it had very little to do with the Prey of 2006, but was critically lauded for it's cutting-edge technology and innovative features.

However, Prey's development grinded to a halt in 1999 when "insurmountable technical problems" appeared, possibly because of the ambitious portal technology the developers were trying to implement. The year 2002 saw the revival of the game by shifting development responsibilites to Human Head Studios. They built a new game from the ground up, this time using Doom 3 technology, but keeping the concepts that fueled the first iteration. This would eventually become the Prey we all know.

And to put things into perspective, here's a video showing the game as of 1998. I know it's hard, but if you try to think about how it looked like in comparison to other games back then, it's pretty darn cool.