Mudcraft is probably one of the weirdest RTS games you'll ever see, and probably one of the best. Not quite a parody of Starcraft, it's an entirely different game all together and has no ties with Starcraft. Mudcraft is fairly easy and comprehensive. In Mudcraft, there is a main 'base', which is a puddle of mud which creates more mud people. The only two resources required to build more mud people is dirt and water which can be found at dirt holes and ponds placed around the map. In each level, a certain task is given to move onto the next, usually involving constructing something early in on the game and as you move on through the game, more complex tasks will be given. Anyways, you get the point.
Quite a great game, one of the best freeware games I've played in awhile. It's even available online as a shockwave game!