You really did well with making the limited shapes stylish. The outlines, color palette, and the camera shake work together with retro-sound to make the game really feel really cool. The background music fits the fast-paced action.
The gameplay works great with the theme. Trying to dodge bullets and stay in the pentagon is challenging in a good way. It's cool that the game doesn't "punish" you for steeping out- you just can't accomplish the objectives, but if it saves you life, it's a good tactic!
I liked that the objectives are randomized, but I got "destroy special enemies" twice :)
Adding the tutorial was a good choice- this is not a VERY complex game, but it has enough rules, that explaining them before made sense.
Over all- great game!