The year is 2186. The player is owner and sole crew member of the M.C.S. Starcross, a mining ship searching for quantum black holes, which are used to generate power. Their luck so far has been bad, but the mass detector alarm goes off as they sleep. What they find isn't a black hole, but instead a giant alien starship that draws them in...
The game originally shipped in packaging shaped like a flying saucer, although when Infocom moved to standard grey boxes, it was re-released in a box like the rest of their line. It is notable as possibly the first game to use feelies for copy protection; a map of nearby objects was provided in the package, and to find the alien craft, the player would need to take the object ID provided by the game, find it on the map, and enter the coordinates from the map into the Starcross's navigation computer.
Tropes found in Starcross include:
- Aliens Steal Cable: Gurthark learned human languages from radio broadcasts.
- Big Dumb Object: The alien spacecraft is a giant cylindrical shape, five kilometers long and over a kilometer in diameter, sent by unknown aliens to search for intelligent life.
- Centrifugal Gravity: How the alien craft simulates gravity. The Invisiclues estimate that the outer surface is spinning at approximately 360 km/h to provide 1G gravity. The center section is in zero gravity, and items thrown from the center spiral down to the inner surface.
- Color-Coded for Your Convenience: There are a dozen color-coded crystal rods and a dozen color-coded slots for them to go into.
- Cool Gate: Two large disks the size of manhole covers, one red and one blue. If they are both placed on the ground, anything (or anyone) placed on one will teleport to the other.
- Copy Protection: Traveling to the alien craft requires entering coordinates from the map included in the packaging. Starcross may have been the first game to use this method.
- Data Crystal: The keys used to control everything in the game are colored crystal rods.
- Featureless Protagonist: As is typical for Infocom games; no details on the protagonist are given at all.
- Friendly Neighborhood Spider: Gurthark is not a spider, but an alien who strongly resembles one and sits in a web made of wires. It is extremely friendly and wants someone to talk to.
- Improvised Microgravity Maneuvering: In the zero-gravity center of the cylinder, you can use recoil from the Ray Gun to propel yourself.
- In the Future, We Still Have Roombas: Small mouse robots clean up anything found dropped on the floor.
- Inventory Management Puzzle: Trying to carry too many items will cause the character to drop something. The large number of crystal rods that the character may need to carry at once is enough to run into this problem. The solution to this is a basket that can hold as many rods as needed.
- Living Dinosaurs: Downplayed; there's a recently-deceased alien that resembles a small Allosaurus.
- Lock and Key Puzzle: There are a dozen colored crystal rods, most of which solve a particular puzzle by placing it in a similarly-colored slot.
- Only Smart People May Pass: The goal of the craft's builders; they are looking for a species intelligent enough to complete all the puzzles.
- Ray Gun: One is found in the armory. Unusually for a ray gun, it has recoil.
- Second-Person Narration: As is typical for Infocom games, the game responds to the player as if they were the character.
- Unwinnable by Design: Like most Infocom games. Starcross definitely falls into the "Cruel" category, with potential failure states including getting the brown rod before the pink rod, not setting up a teleporter outside of the alien warren before getting the violet rod, not getting the atmospheric processor back online quickly enough, or going to the control bubble without all six of the rods that you will need there.