Red Alert 2 and its expansion are the most fun of the series.

User Rating: 9 | Command & Conquer: Red Alert 2 PC
A very fun plot, fun characters, fun all around. This game has some of the best units in the series with a good blend of fantasy and reality. The Allied and Soviet sides are both fun to play and the skirmish mode is just as entertaining as in the previous games. The plot involves the Soviet Union invading America and doing their "take over the world" thing. This game is the most addictive in the series and is easy to learn / hard to master. Especially now that it has been out for a while, it is very much worth the money.