It will come as a surprise but aliens may not be as we imaged and there's a possibility our greatest salvation will come from none other than... plants? Before you scoff at the idea of Mother Earth being our best defense check out Symbiosis, a pleasant tower defense strategy game by The Gamest Studio that will prove to that dead fern that you do have a green thumb!
To fight off the cursed crystal aliens you will place plants on the map and decide whether the plant will grow, attack, or defend by clicking on the plant itself or using [A, S, D] keys. Close proximity to the enemy will allow your plant to attack faster and there are glowing spots on the map that double attack speed when you place a plant on it. To further assist your plants you have the ability to click and drag on one plant and place a symbiotic link to another. The bigger the distance between the two plants the better the benefits are for the receiving foliage. As an added bonus there are upgrades galore to make use of as well as spells that will help heal, harm, or protect.
As far as tower defense games go Symbiosis offers a wealth of upgrade options that will make the fifteen levels go by swiftly and flawlessly. The ability to adjust the difficulty the crystals will offer is a nifty gift that not only allows for better experience gain but also ensures you'll want to play even after beating all the levels. Even though the title of the game would imply that symbiosis would be an integral part of battle it's unfortunately not needed and after even getting halfway through the upgrades available most levels won't need more than two plants on the map to be victorious. Still, the gameplay itself is rewarding and has enough extra goodies to make it worth playing multiple times, especially if you like to complete achievements.