Unknown Enemy is a fanmade conversion mod for Wing Commander: Secret Ops, and an excellent example of what dedicated fans are capable of. Set in the Union of Border Worlds at the time of the Nephilim invasion detailed in Wing Commander: Prophecy, Unknown Enemy casts you as Lt. Colonel Johann Daniels, the Wing Commander for the soon-to-be-retired BWS Dauntless. The Dauntless, like much of the Border Worlds equipment, is hand-me-down Confederation stuff. It's a Bengal-class carrier (like the Tiger's Claw from the first Wing Commander game), and you'll be spending a lot of time flying old Scimitars and Epees outfitted with the latest technology. Unfortunately, when the big bad bugs show up in Border Worlds space, you have to make do with what you have.

Like Secret Ops, the plot of Unknown Enemy is largely advanced in fiction accessible through a viewer included with the game package. The fiction is well-written and keeps you interested even outside the cockpit. Furthermore, since the passwords for the fiction become available only after you complete missions, you can't skip ahead without playing through the game. This also allows the story to take different paths depending on your performance. Like all previous Wing Commander games, the plot of Unknown Enemy is variable depending on how you perform in certain missions, and there are a total of three different endings. The excellent writing in the plot fiction – as well as other little details, like the new ship's cockpits and the CIC of the Dauntless – make the non-gameplay aspects of Unknown Enemy very enjoyable.

Fans of the Wing Commander franchise should be warned, however: Unknown Enemy is extremely difficult. So difficult, in fact, that all of Origin's creations pale in comparison. Several missions are very long, and more often than not you'll make it nearly to the end before your luck runs out, and whatever you're guarding gets torpedoed. Add to this a lot of defensive missions, and Unknown Enemy can often be a frustrating gaming experience. Furthermore, the missions are of variable difficulty; playing on Rookie level may be the only way to make it through some, but may make others far too easy. Finally, not counting plot branching, the game is only eleven missions long. Despite these minor criticisms, however, Unknown Enemy will thrill any fan of the Wing Commander saga, especially ones that have been dying to see what 3D technology can do for old WC1 and WC2 craft. Indeed, many old hands may find the challenge Unknown Enemy presents refreshing. And best of all, it's free – just download Secret Ops, and then install Unknown Enemy on top of it. All in all, a great addition to the Wing Commander series.