Plain gameplay centers on gravity and simple clicks to place defenses. You click to build towers and stop waves. i find the controls tricky but manageable once used to them.
You click to place defenses, and waves come fast, each tougher than the last.
You use simple clicks to place defenses. The physics are wonky, which makes aiming and positioning a challenge.
Most important, use simple clicks to place defenses. Timing is tricky due to wonky physics, so click carefully.
Q: What are the controls? A: Simple clicks to place defenses.
Q: What is the objective? A: Stop waves of enemies.
Q: Are there any stated features? A: Not stated.
Q: What is the main mechanic? A: Clicking to place defenses.