Operation Defensive is a tower defense game but instead of monsters following a track, it's a player. So instead of watching enemies follow a track for no reason, watch them attack a player instead. But dont just stand there--fight back with towers! Towers dont really aim so much, so it's your job to lead enemies into your traps!
You can play multiple different themes, all with unique different enemies and tower skins, and some with bosses.
If you ever feel like the game is too difficult, there are settings for extra starting cash and a heal at the end of each round. Just know that these help settings don't work on bosses. And remember to have fun :D