In this post I will be analysing Tower Defense games, learning about what makes them work and how I could take inspiration from them for my Tower Defense game.
Plants vs Zombies
The first game I am looking at is Plants vs Zombies, a title developed by Popcap and released in 2009. Plants vs Zombies is often considered a core staple of the Tower Defense genre as a whole and is a good place to start. Here I am playing the recently released Plants vs Zombies Replanted on the Nintendo Switch 2, which offers the player a couple of ways to interact with the game. In this version of the game, it supports the Switch 2s touch screen, a controller (or 2 for local multiplayer) or the Switch 2s new Joycon 2 mouse control scheme.
This is the game being played using the touchscreen. This is largely reminisant of an experience that would you get by playing on a phone or tablet. The interface is purely drag-and-drop, in that you drag one of the plants into the grid to place down towers and tap on the sun to collect it.
The new mouse controls on the Nintendo Switch 2 largely replicate the touch screen experience but using an in-game cursor that is moved by using the Joy Con 2s built in mouse features.
Finally, this is the game being played using a controller. This mode of play acts slightly differently to the 2 above. First of all, the player cannot drag and drop the Towers into place, instead, the player selects the tower they want using the L and R buttons and uses the controller to move an in-game cursor that snaps onto each point, then the player pushes A to put a Tower down on that point. To collect sun, the player simply needs to hover over the sun.
The games UI and interaction shifts slightly depending on which control scheme you are using and it gives a good idea of how to adapt a title from mobile to desktop and vice versa, because the Switch 2 using its touchscreen for interaction, essentially acts like a tablet with a 7.9″ screen, while the Joy Con 2’s mouse features emulate that of a PC mouse.
Regardless of the controls, the gameplay of Plants vs Zombies is the same. In each level the player starts out with a blank canvas of turf. The player can collect sun, the games main resource, by moving their cursor over the sun. The player places down plants using a drag and drop UI on a grid, if they have enough Sun for the plant they want to use, then the zombies arrive. The player needs to prevent the Zombies from getting from the right side of the map to the left and into the home. If a zombie reaches the left side of the map once on each grid, there is a lawnmower which gets rid of them once. However, if another zombie reaches the place on the same grid the game is over.
The game primarily consists of offensive towers such as the Pea Shooter, but also contains a few support towers, like the Sunflower which helps the player generate sun, which they will need for placing down most towers and the Wall-nut, which temporarily blocks enemies from moving. The offensive towers includes the Pea Shooter as mentioned and its variations, the Potato Mine and the Chomper which is the games version of a Venus Fly Trap.
What makes Plants vs Zombies effective is its simple and easy to understand gameplay, placing down plants to keep zombies away from the home, but the game does involve some strategy to ensure that the player puts down the towers in the correct place.
Thronefall
The next game I look a look at was Thronefall. Thronefall released in early-access in August 2023 and later released in full the following September. In Thronefall, the player controls a King who needs to protect their castle from invading enemies. In the daytime the player uses the gold they have to make new buildings and to upgrade existing ones, and like Plants vs Zombies it has Defensive towers (homes, which generate coins every night they survive) and Offensive towers like Barracks. Then the player holds down the Space bar to go into the night phase where enemies try to invade. The player can perform melee attacks but mainly relies on their offensive towers to keep enemies away. After the player has defeated the last enemy in a wave, the game goes back into the day phase and the cycle repeats until the last wave in a level has been finished.
Thronefall’s day phase
Thronefall’s night phase
One of the things makes Thronefall interesting is the balance between managing your economy and your defense. The player only has some gold from each night and must spend it wisely, which requires some strategy on its own.
Bloons TD 6
Finally, I had a look at Bloons TD 6, which is, of course, the 6th entry in the Bloons TD (formerly Bloons Tower Defense) series. This iteration of the series marked its transition to 3D and away from the aging Adobe Flash platform used by most of its predecessors, instead being made with Unity. However, the main gameplay here is fairly similar to its immediate predecessor, Bloons TD 5. In Bloons TD 6 you place down towers that are monkey characters to stop balloons (called bloons) from reaching the end. The player starts off with a small bit of cash, and the player gets more cash each time they pop a Bloon.
The games basic tower is the Dart Monkey, and while it is fairly slow to begin with, shooting 1 dart every few seconds, it has 3 upgrade paths with 2 that the player can choose from.
Each Monkey has its own XP, which allows the player to get new upgrades, purchasing the upgrade unlocks it for that monkey throughout the game, however to upgrade this monkey specifically, I would need to go back and spend money to do so. However this is where Bloons differs from the 2 games above and not in a good way.
One issue I saw with Bloons TD 6 was this little button on the bottom right corner. It takes you to a Steam page where, for £9.99 you can skip all the steps of having to unlock a towers upgrades itself and just fast forward that process, and it only applies to that tower. This isn’t a good method of micro-transations and DLC because it allows the player to skip a lot of time and effort using that tower specifically to get it upgraded. The base game is £11.79 and, at a quick glance at the other things you can purchase for it, you can also just skip straight to Rank 30 for the price of £7.39.
You can also get expansions for the game but none of them seem to be recieved that well on Steam.
The game is playable without having to spend any more money, however, and the gameplay experience is overall good. The game gives you a wide variety of monkeys to use as you can see below. Theres the Dart Monkeys of course but theres also snippers, the Hero Quincy (who can automatically level up), bombs, tack shooters, and of course, Defensive towers like the monkey who shoots glue to slow down bloons.
