As someone who programmed this game, pro tip: Stay in the middle on the right side to give yourself more time to destroy enemies as they spawn and to avoid them spawning on you. Backing up to the divider makes it a lot easier to pick off enemies coming from different angles. I would focus mainly on the right side and use the left when you have a decent amount of health (focusing on the left leaves you open to attack) Also you can use the divider to lock your position making it so you can move the left without the right.