Fascinating game!
Thank you so much!
About controls - the main idea of the game is to control each leg. You have to raise particular leg to avoid missiles, to not step on something and to step on someone by particular leg. There are two lines of enemies, and player have to chhose leg correctly to survive in the battle. This is the main idea of the game. Just holding D - is nothing new.
I don't know what thing makes you remind "Starship Troopers", but you can meet "private Rico" in the game (with a different name - we have A. RICO), becouse of Robert A. Heinlein is my favorite author. And "Starship Troopers" is a book that I re-red many times.
But setting is close to Avatar as for me. There was no our goal to make something like Avatar at first, but we had some ready-to-use resources from our previous game that convinced us to go this way.