In this excellent logic and speed game Qilox, you must try to capture more than 75% of the arena whilst avoiding enemies. When you enter the arena, you draw a trail behind you, which divides the arena. Sections of the arena that have no enemies in them are captured. Reflexes, anticipation and good sense are required to pass the levels more difficult.
Arrow keys or WASD to move. You can also use Space bar a limited number of times per level to reverse all the spheres in the arena.