The First 15 Minutes of Command & Conquer: Red Alert (PlayStation)

Copied from MobyGames:

What if Hitler never existed? Einstein pondered the question and created a time-machine to eliminate Hitler as a young man, thus preventing World War II as history remembers it. However, Einstein stopped one evil only to create another - because Stalin's Soviet Union is now poised to conquer Europe... and Allies must stop them!

Command & Conquer: Red Alert can be considered a prequel to Command & Conquer. Like its predecessor, it is a real-time strategy with an isometric semi-top-down perspective using 2D sprite graphics engine. The player takes control of either the Allies or the Soviets, as he battles for destiny of the planet. Gameplay features are similar to those of the previous game, including building a base with some defenses, massing units, harvesting resources, etc. The game has a variety of environments in its missions, adding some indoor missions that use only infantry units.