Sunday, March 29, 2015

Game Balance Analysis of Bloons TD 5

I.            Overview
Bloons TD 5 is a top-rated casual tower defense game on both webs and mobiles. The player allocate points to buy monkeys or similar things (as towers) to protect the base from the bloons (balloons). Link of the game: http://www.kongregate.com/games/Ninjakiwi/bloons-td-5

There is no multi-player, so I will focus on the balance in “Game versus Game (GvG)” and “Player versus Game (PvG)”.
I.            GvG
The difficulty/mode system is structured as below:

1.     Modules
There are 3 similar modes in this game. Daily Challenge and Special Missions are unlocked based on the player’s rank.

a)      Normal
The original and default systems of levels. Levels are categorized by different maps/tracks of difficulty.

b)      Daily Challenge
Seems to be a new feature. A different level is up there every day. The player can go back and check out the previous ones. Daily Challenges are really challenging, much harder than the Advanced maps in Normal Module.

c)       Special Missions
There are a few distinguished gameplay modes than the Normal levels. Some are unlocked based on the player’s rank. They introduce new gameplay into the existing game systems. These games need different strategies to beat. It is hard to compare the difficulty and other factors with the Normal games.

2.     Maps/tracks (+ Modes)
As mentioned, Normal is the original/default playground in this game.
The game has a complicated difficulty system. It not only categorizes maps into five difficulties: “Beginner”, “Intermediate”, “Advanced”, “Expert” and “Extreme!”, but also provides 3 modes for each map: “Easy”, “Medium” and “Hard”. (There are also more different play modes being unlocked for each map based on the player’s rank: Deflation, Apopalypse and Sandbox. But I will not talk about them in this essay.)

For each map, the difficulty of different modes is simply being tuned by the number of lives and the enemies: 
Maps determine the distribution of areas having different influence on the enemies. For instance, in Beginner maps, there are more areas that are very influential and the player would have less chance placing the towers at weak spots which leads to the loss of lives. In contrary, the advanced maps tend to have fewer “good” spots which means that the player needs to choose carefully when they place a tower.

Also, the number of branches varies from map to map. The more advanced a map is, the more branches.
In addition, it feels that the increase of enemy power is also being tuned with the difficulty of maps. (Not sure.) The more advanced a map is, the more difficult it gets through beating various enemy waves.

a)      Beginner: Sole path, bigger influential areas, and less challenging
Beginner maps are very simple. They are definitely the best/safest places to start the game. The player can easily figure out how the bloons move and place the towers accordingly. At the same time, the player can learn the UI for the maps (distinguish paths from areas that can place towers, or familiarize towers and their power-ups). The player can also learn a specific tower super well by practicing with the map that the tower works best with, and familiarizing patterns. But sometimes feel they are too simple and boring.

b)      Intermediate: 1 or 2 path(s), medium influential areas, proper challenges
Intermediate maps are tuned finely in the middle of Beginner ones and Advanced ones. There are some variations in maps, such as loops and binary branches which converge later. It is more fun to play compared with the Beginner’s maps.

c)       Advanced: 2 paths/branches or more (dynamic switchers), smallest influential areas, super challenging
Advanced maps are way harder than the other ones. There are always multiple paths and sometimes the switcher connecting various branches change after each round.

d)      Expert
No access…

e)      Extreme!
No access…

1.     Enemies
The enemy system is relatively simple compared with the play modes and tower design. All the enemies are balloons (Bloons). The basic one is destroyed when being hit by a single shot. The advanced ones have more layers, which means it needs more shots to destroy them. Except the ordinary ones, there are also another type of Bloon called Camo. The Camos camouflage themselves, so only specific towers/upgrades can detect and damage them. Some Bloons (lighter ones) also move faster.

The game helps the player distinguish various Bloons by their color/texture/size/shape and speed.

2.     Towers
There are 17 towers and 2 consumables in total. Each tower has a different behavior and 2 upgrade paths. Towers get XP and level up to unlock new upgrades. The towers are balanced because of their uniqueness in behavior and the increasing power as leveling up. I don’t feel anyone is obviously stronger than others.
Also, because of their varied costs, towers tend to be used in different stages of play. As a general trend, the more pricy a tower is, the more powerful it would be.
Since the behaviors are very different from one to another, it is hard to compare only the attributes. Below are specs of towers in level 1 (Advantages):

1.     Reward Systems (Overlapped with PvG)
The direct reward for the player is experience points (XP). The player also ranks up automatically by gaining XP. As the player ranks up, new towers, upgrades (and enemies) are being unlocked.
In short, the reward loop is: XP -> Rank up -> Unlockables.
This game has a reasonable ranking up pace, which feels similar to many other games. Sometimes duo objects are being unlocked when ranking up, which is a satisfying moment. However, the game introduced very few enemies (officially, but they already appeared in the play) and a LOT of towers/upgrades at the earlier stage, and started to throw out a LOT of enemies afterwards. I prefer to learn powers and enemies hand in hand/in turns, rather than doing one continuously and then another.

2.     Playback Speed
The game provides two speeds for the player to choose between during the play: Normal and Fast. I think the Normal is too slow (but it is fine since it is the original pace). But the Fast is too fast, if anything happens, the player wouldn’t have enough time to react, such as placing spikes or explosives on the map.
In some TD games, there is also a Stop/Cease button which allows the player to freeze the game and do some urgent operation to rescue some lives. I think it will be great if the Cease button is added to this game.

3.     Special Agents
The game also offers a lot of in-game purchase. I think they can definitely help the player beat the levels easily and I am not focusing on them…

Overall, the GvG is well balanced in this game. The progression felt very smooth. And it provides enough choices for the player, high longevity (although each play can already be super long and time consuming...) and appropriate challenges.

I.            PvG
Besides the different aspects listed above, I also want to talk about the balance between the player and the game:

Since the game provides many difficulties for the player to choose from, the player can easily tune the difficulty to fit for themself (GvG). But still, there are moments that I felt the game was throwing too much information all at once and I felt that was totally overwhelming. Most of them happened in learning phase (when the game introduced me new towers/power-ups in as rewards) instead of the play phase.

1.     UI/UX design
Good UI system teaches the player how to play by itself. Although the game has decent graphics for UI, it takes a while for a player to figure out what to do next and learn how to do what by themself. And the game has no tutorial even during the first play for a player.

a)      Game Flow
Only have some tips, without any tutorials/walkthroughs is confusing.
Notes:
“Didn't know what to click on first. Took me 5 seconds to figure out what to click on.” This was not so bad. But still “...felt like having a little more instructions or tutorials that could walk me through some basics would prevent me from getting lost.” Personally, I think having a compact game flow is super helpful for web and mobile games. This is somewhere the game can improve.

b)      UI Layout
Giving lots of specs for each tower, it took me quite a while to find out the attack modes selection (First/Last/Close/Strong) and the where to upgrade the tower.

c)       Icons
The icons are designed visually pleasing and convey its function pretty well. However, not having any feedback when a tower/upgrade is first introduced to the player (highlight, or an animation of the icon moving from the reward interface to the in-game position) makes the player easily lose track of the new unlockables.
I also noticed that, sometimes, the game seems to reward powers that work well for the current level. So it somehow makes up a little bit for the problem of not being able to track the latest unlocked powers.
Notes:
“Especially hard to find out which upgrade belongs to which tower.”  It is hard for the player even to find out the latest gained power, owing to the inaccessibility to all the upgrades for a tower. It seems that the UI couldn’t teach well by itself.

2.       Reward Systems
The player can earn experience points by playing the levels. As the player ranks up, new towers, power-ups (and enemies I believe?) are introduced at the same time.

Notes:
“The game introduced too many towers and power-ups at the first play. Needed some time to connect the icon with its functions.”

3.       Challenge/Narrative/Interest Curve
a)   Within a Level
Within each level, as the player beats waves (rounds) of enemies, the game gets harder as the overall trend.
The increase of difficulty feels unobvious in simpler games (maps/difficulties), however, it can be super challenging in more advanced ones.
To be more specifically, I kept spamming “Play” button in easy modes, since even if I did’t do anything, the current powers could survive many rounds by itself. In contrast, in advanced levels, I always felt that my towers were running behind the enemies and I made irreparable mistakes in selecting and placing towers.

b)      Out of a Level
Players do get better as they learn more about the game. So a new player wouldn’t always stay with the Beginner’s maps, s/he will jump to the advanced ones and maybe go back and forth. The gaps between different difficulties of maps are pretty big, but the game managed to fill the gaps by having three minor levels of difficulty for each map. In this case, the player can tune their challenge curve by themself and wouldn’t be restricted by the game systems.

To sum up, although the game is top-rated, I think the PvG part is not perfectly balanced. The game leaves the choices to the player which reduces the chance that the player feels overwhelmed or frustrated. But it failed to convey and display everything nicely. A better UI/UX or game flow would help.

II.            Conclusion
The game is overall pretty balanced. It does a good job in balancing content statistically (GvG). However, there are too many details and various scenarios in the game, so it couldn’t teach the player everything clearly/step by step, which sometimes cause confusion.

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