Total Annihilation is a RTS that just does not fail to impress at every turn!
The game starts you off choosing between 2 forces, core or arm, each of which have their own unique units, but with an equivilent unit in the other army. The game has multiple campaign based missions for both armies, however the games strength is in the skirmishes that you customise yourself, getting to customise teams, amount of players, colour, army, and also a map from a large selection.
At the beginning of a skirmish, you start just with your commander, who is a strong all round unit that can build buildings quite quickly and also has a lot of health and can attack enemies. However he can only build basic buildings. The idea is to collect both metal resource and energy resource, by building metal extractors (for metal) and solar stations or wind generators (for energy) though later on there are much faster ways of collecting these resource.
With these resources, the commander can build a range of buildings varying from docks, to airbases, to turrets and metal extractors, the airfield and a few other buildings being able to build their own construction units which can in turn build more advanced buildings than the commander can.
The idea of a skirmish is to conquer your opponents by either destroying their commander, or by destroying all of their units (this can be customised before starting the match).
The huge variety of units, buildings, maps and strategies means that this game just does not get boring- you can conquer by land sea or air! This game may be old, but it certainly still remains a strategy classic; and well worth buying if you can find it!