Most levels can be finished without using any sun-producers, but these have been tested. These are the levels with tested strategies. * Level 2-1 * Level 2-2 * Survival: Day (Hard) * Survival: Pool (Hard) * Survival: Roof (Hard) * ZomBotany * ZomBotany 2 * Bobsled Bonanza * Zombie Nimble Zombie Quick * Pogo Party * Seeing Stars * Art Challenge Sunflower * Art Challenge Wall-nut * High Gravity * Unsodded * Big Time * Sunny Day * Day It's very difficult, but not impossible.