I sent the boss to the hospital in 26. day and it take me 1 day to send him to the grave. I think you should change the number of objects and make the game harder
I finished at my first time. and the only secret is DO NOT BY BAZOOKA BEFORE BROWNING.
I also think that machine gun vehicles are more dangerous than tanks. once you get both bazooka and browning, get vehicles with browning and tanks with bazooka