If you're a fan of side scrolling shoot 'em ups, Chalk is a really inventive take on the genre.
You control a girl, flying over a blackboard background, using the keyboard. To destroy shapes and enemy ships that come your way, you draw lines over them. You can draw shield for yourself, connect approaching missiles to enemies to fire them back, or simply connect dots to blow stuff up.
Despite being unusual, it's really easy to pick up, and very well done. You'll be drawing away enemies in no time, and boss fights are really good. The art work, all drawn in a chalk style, is fantastic, and like the gameplay pretty unusual! For a freeware game, Chalk is very well realized and executed.
Chalk's sound is brash, but helps with the gameplay, as there are various effects when you successfully draw over a dot or enemy. The music has a rough and ready feel to it, and while it's not that professional sounding, it suits the strange drawn style of the game in general.
Chalk is a unique shoot 'em up which is really accessible and fun to play