Best random buy for me is Original War. It was in a pack with Fallout Tactics I wanted, and some game that was really, really terrible, the pack for like 49 Francs (about 8€)
You probably never heard of it, OW was a RTS with - unfortunatly for it - poor graphics and an awesome plot and gameplay.
What I liked is that it was a RTS with a limited number of guys for the whole campaign. Basically, USSR and US (and some other guys, but spoiler) sent an handful of troops back in time to secure an all-powerful ressources, the Alaskite/Siberite (depending on the time continuum). So you've got those few guys, with exp. points, level, and stuff, and you won't get any more, so preserve them. Same for the guys in front of you (even though they start with more people in the campaign).
Anyway, that was one of the best game I ever played. Top 5 in my book, and much better than Fallout Tactics (which was not that good anyway - but it was the reason I bought OW)
As for more famous game, Vietcong I