One of my favorite all time games is Outpost 2, but at the same time it might be the most disappointing in my opinion. The game was set up with so much potential, but they did absolutely nothing with it.
The campaign was short and had no variation between the two available factions. The two factions were only really different cosmetically. Once the game reached a certain point, nothing would change. It would be the same fully upgraded colony. The game is a very difficult fight for survival on a new planet, but once you make your colony pretty much self sustained, there is nothing else to do. They might have made more to do once you make yourself really advanced.