Press space on the main screen, arrow keys to move, and left click to shoot a bullet . Enemies will spawn randomly, which you must either avoid or kill. Every so often, water will appear. Each water will fill your water meter back up to full. If it reaches zero, the game ends.

In GMS2 trial version, you cannot export games, so if you want to play it after the event, you will have to make an account, then download the game on github. After that, open the game and press F5 to run it or click the l> sign near the top left corner.