RED ALERT 2
Red Alert 2 was awesome because it was the coolest RTS back then. You could control tons of Allied and Soviet units and command them to destroy eachother. It was super fun back then and still is today.
Today I play Red Alert 3 and honestly it isnt that great. I still like to play it. But it isnt as influencial as Red Alert 2 as far as fun-factor and art. I felt like Red Alert 3 was more cheesy and nothing really looked believable.
Red Alert 2 had great graphics for its time. And as for art direction, I would take is concepts of future death machines and commanding forces any day. It was the ultimate game to deal destruction.