Altar Interactive's "Original War".
Ok, lemme pitch it to you:
It's an RTS, but with a difference. Rather than starting out with a builder and going from there, you start out with a bunch of dudes (and dudettes). Each dude can do pretty much anything depending on what class he is (there are 5 for each side, Soldiers, Engineers, Scientists, Mechanics and Special Soldiers). The kicker is, you can't train new men from a miracle barracks building, if a soldier dies in the field, he's gone forever.
Every character has their own skillset, which can develop as the game goes on. This means that you'll grow to value each member of your team (especially in the single player mode, where there are a lot of interesting characters!), and a single death can be something that your faction can't easily recover from.
Add to this what has to be the original storyline and setting you'll ever see in an RTS, and you've got to wonder why so few people have played this game...
There's a demo floating around somewhere, if you want to give it a try. (I'd strongly recommend it) The full game can be brought on www.sprocketidea.com for about a fiver.