

It is a much more active game thats closer to a RTS than a typical tower defense. The enemies are also aggressive and will attack and destroy towers. Instead, the enemies will try to approach from the player's weakest coverage. the gimmick of this one is there is fixed routing or mazing. Revenge of the titans - some people don't like to call this a tower defense.

while a player could play it like a normal tower defense, the game rewards players for making orcs suffer horribly through multiple traps. the emphasis on this tower defense is scoring through combos. Orcs must die - already mentioned in comment thread. unlikely to find a random person online to play with though as the game is old. It also has a pvp mode so you can go head to head against a friend. Sol survivor - great for people who don't like to maze. Since defense grid is already a well known gold standard, I'd like to add some other suggestions

I don't know warcraft 3 tower defense maps, so it is hard for me to recommend something similar. Some focus more on mazing, some on progression, some on cross-genre, and some are pvp based.
