Shortfall

Survive as long as you can! Your character will automatically shoot enemies coming from the left or right.

Look out for special zones spawning around you every 20 seconds, and try to stay inside their radius to receive a bonus:

Gold zones spawn coins

Red zones spawn medkits

Blue zones boost your weapon (damage and rate of fire)

You can purchase upgrades in zones using your coins:

Gold upgrades make more and more enemies drop coins when killed

Red upgrades increase your max HP

Blue upgrades increase your base damage