Tactics play a role in Supremacy to be sure, but the game is won or lost virtually everytime in a battle of attrition that is decided by resources. As the game stands right now, whoever controls the most planets wins, period. There is a strategic element involved in planning your moves to ensure you capture planets and starbases, (research), in such an order so as to give you the advantage over your opponent, but once you've got them, it's a set-piece battle of attrition for the most part against the computer.
Now against another player there can be a more involved game... if your opponent chooses to use cloaking technology, for example, you have to employ research ships to discover his movements, etc., but that's about the extent of it.
In my opinion, it is somewhat similar to GalCiv, only without the strategic depth (and diplomacy) or grand epic scale. On the plus side, there is ground combat in Supremacy, but it tends to play a minor role in most games since it also is usually a game of attition. If you have more planets than your opponent you will crush them with superior numbers and technology, ad nauseum.
Supremacy is a fun game, good for a two or three hour rumble in space from time to time, but it will not quench your thirst for a grand, epic conquest of space. It's kind of like playing in a single basketball game as opposed to taking part in the entire NCAA tournament. You decide which you would rather do in a given session and then decide which game you would rather play. Just don't look for anything deep and involved.
P.S. It could get a lot better IMO if certain elements were included to give the game more depth... there are some decent ideas out there. Hopefully we'll see them implemented in the future!
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