Press the arrow in the corner to open the shop, and buy turrets from there. Press the play button and watch as your turrets shoot down the enemies! Click on a turret to view it's upgrades and range. Note: If a turret is shooting out of it's range, that just means it's range is too big for the circle to comprehend.
This is a version of Mathy Tower Defense, except with almost all of YOUR suggestions! Typing underwater will switch the map to underwater, typing hell will turn n boss music and change map and typing surface will switch the map back. If you have suggestions, put them in the comments-there's a good chance I'll add them. If you see any enemies but they die so quickly you have no idea what they do, comment below and I'll try to let you know!