If it weren't for Melan's Unbidden Guest I think The Unsung Villain would've won the Classic Thief Experience contest back in 2008. This little gem of a mission is basically Assassins and it's just as fun as the original mission. After an assassination attempt, you follow your would-be murderer back to whoever hired him and from there you have to find a way in. The story is pretty thin but it's not that important. The Unsung Villain shines because it pushes all the right buttons. The cityscape is small, medieval and very reminiscent of the tightest, smallest bits of Assassins except with a Thief 2 coat of paint, which works very well. While it is not sprawling, it still manages to feel complex and is very pleasant to traverse.
The main course of the mission is Lord R's manor, which is quite interesting as it bridges the gap between Thief 1 and 2 style-wise. The manor is old looking, with red and blue brick, and most of the interiors feel cold and a bit stern, but the lord recently refurbished his guest wing with all the latest Victorian fad. It looks gaudy and a lot more modern than the rest, which is an interesting juxtaposition. The manor as well as the city have appropriate ambient sounds here and there, even though I wish some areas had a bit more as they feel a bit bare in that department. The sound is especially good in the guest wing, which uses some of Thief 2's most iconic loops to great effect. The mission isn't too difficult and finding all the loot isn't an impossible task since all the secrets are relatively easy to find. The mission also features a really good Thief 2-style automap that is very useful and very well drawn.
The Unsung Villain is, all in all, an excellent mission that does everything it tries to do just right. It's a great classic throwback and an underrated little treasure. It won't take you more than hour, too, which is perfect if you want a little bit of quick taffing.
star 9 / 10