Flying Robot Studios have placed their game Warfront Defenders: Westerplatte up on Steam via Early Access. The game is best described as a hybrid between Tower Defense and Real Time Strategy games and is centered around events in World War II. Some of the features the current games has includes the following..
Destructible environments
Position your soldiers anywhere, use cover tactics, some of the areas are more exposed than the others
Equip/Add health and Upgrade/Downgrade your soldiers during battle
Build fortifications, lay mines to slow down or kill enemies
Reactive enemy AI, changes strategies based upon your movement
Overwhelming bosses like Battleship Schleswig-Holstein, Stuka dive bombers, snipers
If you are interested, the game is currently 30% off on Steam and priced at one $3.49