These unique units produce a variety of choices for the player-- not just 12 choices per race, but in fact hundreds of choices, all of which have practical applications since combinations of units are typically more useful than just one type of unit alone. Add the fact that players must carefully select their units in order to counter what their opponent is up to, and decide not just what but when and where to produce units and you are left with a game that is very difficult to master, but extremely easy to learn. Chess is strategically deep for similar reasons -- the nuances of the interactions of the pieces and the timing associated with them are extremely difficult to master, but the basic rules are easy to learn.
The second core thing that greatly enhances Strifeshadow's strategic depth is the fact it will be a well-balanced game. Balance in this context means that if a player has several choices in front of them, it is not completely obvious which one is actually the best, even though it is completely clear as to how they are different. Another subtlety of balance is that of how the player spends his or her time. One example of this is the distinction between micro-management and macro-management oriented playstyles that is often drawn in RTS games. A micro-management oriented player tends to focus on battles heavily, giving orders to individual units to win victory. A macro-management oriented player ignores battles for the most part, instead focusing on streamlining their production so as to overwhelm a micro-manager. Both are viable in Strifeshadow, and this is only beacuse the player must pick and choose where to spend his or her time, and cannot manage to do both.
Although Strifeshadow will be balanced during the beta testing period, there are a lot of subtle behind-the-scenes features to make play balance a realized state with minimal testing. Should play balance issues emerge after release, they will be remedied.
Strifeshadow, Ethermoon Entertainment and their respective logos are trademarks of Martin Snyder