Science fiction is at its best when it is used as a tool to explore the human condition. Science fiction games have an extra hurdle of not alienating players by making the sci-fi overly complex; to do so can disengage the player from the story. Gateway mostly succeeds at both before faltering in the final act.
As the story's hero, you play a prospector hoping to gain fame and fortune by going off on solo space missions to collect artifacts from the mysterious Heechee race, whose equipment you are immersed in but barely understand. Half of the game is learning how to use and manipulate the various Heechee tools and machines you come across, and half the game is solving standard fare adventure puzzles. Thankfully, learning the alien technology is often a fairly simple exercise in interpreting basic symbolism or at worst guessing and checking. And for the most part the rest of the puzzles are only moderately challenging. I required only a few hints for the duration.
The game design is identical to all the early Legend games, with the option of playing the game as a straight text adventure or using a graphical point and click interface reminiscent of the frame hell of Geocities websites and requiring the user to choose from a list of every possible verb the game understands rather than the standard eight from LucasArts games of the time. While I can't imagine any sane person strictly using the mouse to play Gateway, the verb list is occasionally helpful for reference and the still pictures are helpful in visualizing puzzles in addition to being gorgeous.
The plot itself is engaging, slowly unraveling while allowing the player to tackle one of several puzzles at any given time. This was a huge relief as sometimes I just needed a break from one puzzle; several times when I came back to a tough one the solution became clear. The alien worlds you visit are for the most part captivating, each with their own technology as well as flora and fauna. The most satisfying areas of the game for me were the puzzles surrounding the beast (with unexpected drama with every step) and the world where you find a stranded prospector (as every puzzle has a moral and immoral solution). I did find one, uh, bug involving a spider that required some finesse. And there is no way to put the game in an unwinnable state unless your only save is during one of the game's few local time limits.
Unfortunately, the end game is a disappointing mess. The sci-fi becomes Inception level confusing without the dramatic appeal, and the puzzles become more obtuse. In particular, the puzzle involving the goblin takes some guess-the-author's-mind wizardry, and the final puzzle involving (Spoiler - click to show)the VR manual is a disappointing whimper. The ending itself sees the player in a passive role and is also lacking a satisfying resolution. Still, I'm quite glad I played Gateway and look forward to playing the sequel.