If there are bugs(not lag), click on the magic wand and maybe, it will take care of it Click on a plant then click wherever you want to place them. You'll discover what the plants and the zombies(and mutated zombies) can do in game To get sun(cost of the plants), put your cursor on a moving sun, you don't need to click it To get the green booster, kill a fat zombie, then take the booster that comes out of it, like a sun. To use the booster, tap on the booster icon(top right corner) and then click on a plant that you placed : it will use its special ability
If you have a slow computer, there will be a lot of lag (at the beginning it's playable but then it's crazy !) Knight zombies can't be killed by watermelons, only by cakes or trucks. For the other zombies, their abilities are pretty understandable. Check out my Clash Royale creation (this one works) !