CHECKLIST -- init project files [DONE] -- HTML structure [DONE] -- js file included [DONE] -- js file checker [DONE] -- create a player [DONE] -- shoot projectiles [DONE] -- create enemies [DONE] -- detect collection on enemy / projectiles hit [DONE] -- remove off screen projectiles [DONE] -- colorize [DONE] -- shrink enemies on hit [DONE] -- create particle explosion on hit [DONE] -- add score [DONE] -- add game over UI [DONE] -- add restart button [DON] -- restart game [DONE]