You are Tentacruel! Use the arrow keys to move. To get points destroy buildings by pressing space when touching the buildings. Get to 20 points, and you win. The Tentacools heal you. Try to dodge the Zubats, Pidgeys and Butterfrees. They hurt you. If you get to 0 health, you die.
I give full credit to the "Pokemon: Indigo League" episode "Tentacool and Tantacruel" which this game is fully based off of.