Game Idea Giveaway - City Basher

Last year, I wrote up this game idea giveaway for Emanuele Feronato to post on his popular Flash game development blog. But after waiting for many months without a reply from him, I decided to post it here so I can finally share it with all of you!

Be warned, this giveaway is epically long. My longest yet.

...continued from The Game Idea Giveaway Thread

Request by triqui:
  • what sort of game idea you're looking for
    intriguing but difficult-to-implement ideas will do
  • what your goals are in making this game
    I would like to make a post about gameplay ideas

The idea: City Basher

In short, City Basher is a physics-based multiplayer artillery game combined with a trading card game (like Magic: The Gathering). It's a competitive game where you try to knock over your opponent's buildings, and it is designed to work very well with microtransactions.

This game is founded on the wide appeal of vanquishing strangers over the Internet and the primal joy of toppling carefully built towers of blocks, without the bother of having to actually build them in the first place. For that reason, the game is primarily a quick deathmatch experience, like most online multiplayer games aimed at bloodthirsty teenage males. Though there is also the option for team play and casual matches between friends.

Like other multiplayer artillery games, most notably Worms, each play session is short, measured in minutes, and involves only a handful of players. But as a game supported by microtransactions, players maintain a persistent identity across play sessions, retaining their avatar, items, resources, and statistics. This is the approach taken by Gunbound, a multiplayer artillery game that was one of the earliest successful microtransaction-based games to establish itself with Western audiences. Gunbound made its money by selling avatar decorations. City Basher will do that, and more. Much more. [cue dramatic music]

Each play session takes place in a 2D arena, seen from the side. The arena is full of buildings, structures of physically-modeled blocks, some solidly stacked, some precarious. At first, the arena is a neutral territory, dominated by a huge monolith in the center. Players take their places in the arena, each one piloting a vehicle with a mounted cannon or two. The game begins, and players open fire on the buildings to convert them to their own color. When one player topples an enemy building, a new building rises up in its place, owned by the player who placed the final shot and color-coded accordingly. The session ends when the neutral monolith in the center is toppled, and players are awarded their final scores.

The play format is very flexible. The game is not zero-sum. Players play for points, not simply to defeat their opponents. If you destroy one of my buildings, you are rewarded and I am penalized, but your success does not depend on my failure. It merely happens to coincide with it. Players are never eliminated from the game, though they are free to leave at any time - their buildings are simply replaced by neutral ones. And most arenas would support a varying number of players depending on how many people are available. If there are slots open, new players can join an existing game. This is very important for a casual multiplayer game like City Basher.

Since this is a game supported by microtransactions, we want to make everything into an item that can be bought and used up. Not that players would necessarily have to pay real money for everything in the game, but it's nice to have that option. What this does is set up the expectation that things can be bought. If players get used to paying for items with virtual currency earned in the game, they'll be more open to paying real money for the really valuable items they might want later on. In City Basher, these items consist of vehicles, weapons, buildings, arenas, avatar decorations, and general enhancements.


An important part of most any game is the movement, how a player gets around in the world. In City Basher, vehicles encapsulate this piece of the gameplay. Every player starts with a basic vehicle that is like a slow-moving tank. But other vehicles could be bought. They might move faster, they might be smaller or larger or shaped differently, and some might even fly or hover or jump. However, movement isn't the focus of this game, so it should be kept fairly simple. As a result, each vehicle is controlled in more or less the same way - that is, with the arrow keys or with the mouse, following the mouse cursor. Also for simplicity and to minimize the effect of lag, vehicles would not be able to collide with other vehicles or knock over buildings. Instead, they would pass through other vehicles harmlessly and treat building blocks as immovable terrain.

The real fun of the game starts with the weapons. This is the part that puts the artillery in artillery games. As is typical in the genre, the basic weapon is a slow-firing cannon, which the player must aim by setting the angle and power of the shot with the mouse or keyboard. There are a lot of ways to set up the specific controls for this action, so I won't go into too much detail here. The easiest way I can imagine is just to click the mouse to set up an attack, move the cursor to set the angle and power, and click again to fire. This way, you could fire off a quick shot by double-clicking. Since attacking is a focus of the game, different weapons could even have different methods of control, as long as they support both the keyboard and the mouse.

For a game like this, there would be dozens, if not hundreds, of different weapons to buy. Some might be variations on the basic cannonball, maybe with extremely high mass for extra power on stable buildings, or a small but extremely bouncy ball that can ricochet off multiple blocks and quickly take out more delicate structures. Some weapons might shoot several balls at a time, or an explosive shell, or several balls chained together. Others might be a different kind of weapon altogether, like a rocket launcher or a block-melting death ray. There are a ton of possibilties here - just look at a game like Worms for example. Each weapon would have a certain reload rate, a waiting period of anything from a half a second to several minutes before they can fire again. This would help to give the game a more strategic, turn-based flavor, without the turns. For this reason, there could also be weapons that are weak but useful because of their rapid firing rate. Another part of the strategy would be in selecting your arsenal, since you can only bring a limited number of different weapons into each game.

The other focus of the game is on buildings. Weapons are what you use, and buildings are what you use them on. So naturally, you'd be paying a lot of attention to them. Just like there are different types of weapons, there are also different types of buildings, each one a particular configuration of blocks of various size, shapes, and masses. Some have special side effects too, that are active while the building is in play. For example, one building might increase the mass of all your other buildings while it is in play, making them harder to knock over. There could even be a building that increases the strength of gravity over the entire arena, or doubles your score from every hit. It's a lot like the way that different cards have rule-changing effects in games like Magic: The Gathering or Pokemon.

The similarities don't end there. City Basher handles buildings just like cards in a trading card game. You don't build buildings, you collect them. Each player has a bunch of building cards in their collection. Each of these cards represents a particular building type, though a player might own several copies of the same card. When you join a game, you choose a set of cards from your collection that will be available to you during the match, in the form of a deck of cards. Like any trading card game, there is a limit to the number of cards that you can include in a single deck, and a limit to the number of duplicates you can use of the same building card. This means that you have to put some thought into which ones you choose. Some players might even spend more time just designing their decks than they do in playing the actual game!

When you choose which deck you want to use for a play session, this determines the type of buildings you can get in the game. Whenever you are due to have one of your own buildings pop up in the arena - say, when you topple an opponent's building - a random card is taken from your deck, and placed in the arena as a new building. When that building is toppled, the corresponding card is returned to your deck. That means that if you have three copies of the Citadel of Awesomeness card in your deck, you can have up to three Citadel of Awesomeness buildings in play at any time. And if you have no more cards in your deck when you destroy an enemy building, that building is replaced by a neutral one instead. The most powerful buildings are designated as Legendary buildings, and can only sprout up in special Legendary building slots, of which there might only be one or two in any given arena. Legendary building cards are ignored when drawing for normal building slots. This helps keep the game balanced.

Finally, there are the arenas, where the games take place. These are not items owned by individual players, but the effect is similar, since players may have to spend points or money to access certain arenas. At its core, an arena is a 2D map of indestructible terrain with a bunch of building slots scattered around - areas on the ground where a building may sit. One of these areas is reserved for the monolith, the giant neutral building that ends that game when it is toppled. The arena defines what this monolith looks like, as well as the deck of possible neutral buildings that may pop up. Each arena also specifies how many players are allowed at a time and where they appear at the start of the game. Lastly, each arena defines its own physical properties like gravity, air resistance, and wind, as well as the background graphics and sounds that make up the feel of the place.


In a typical microtransaction-based game, there are two types of virtual currency involved in the in-game economy. One is earned through playing the game, like experience points. The other is bought for real money, which is how the developers make a profit. City Basher is no exception. Players can exchange their real money for a virtual currency we'll call Coins, and they can also earn another virtual currency, Points, through gameplay. The names used here are just for convenience, by the way - in the actual game you'd probably want something a bit more glamorous.

Players can earn Points in a number of ways. The most common way to earn Points is to knock down an opponent's building. You don't have to knock it down completely to get points - you only have to reduce its height with your shot. Each type of building is worth a certain number of Points to topple, and you get a fraction of that for every fraction of the building's original height that you knock over. However, you only get to replace it with a building of your own if you deliver the final blow, one that topples the building completely. The advantage to having lots of your own buildings in the arena is that at the end of the game, when the monolith falls, you receive Points for each of your buildings according to their remaining height and Point value.

This results in a system where new players can join in the middle of an existing game without having any unfair advantages or disadvantages relative to the other players. It also encourages players to stick around for the whole session in order to earn bonus points at the end for their remaining buildings. At the same time, no one is bothered if they leave, since their buildings are replaced by neutral ones which yield Points just as readily as player buildings. And it works just as well for team games, since players on the same team simply share a single color, and don't earn any Points from toppling their teammates' buildings. On the whole, it is a scoring system designed to reward good players, without punishing the players who aren't as skilled. This keeps the game accessible to casual audiences. And that means more money for you.

So, let's talk a little more about money. Specifically, let's talk about what players spend it on, and why. First of all, let me emphasize that the game itself is free to play. Players are not spending money just to play the game, they are spending it to buy virtual items inside the game. This is what it means to have a game based on microtransactions. Second, it is important to understand why players would want to buy these imaginary items at all. Players will spend money not so much as an exchange but as an investment. It's not about exchanging value. Why would a player give you real money for nothing? It's about investment. A player gets some significant value through playing the game for free, and then they think that they could enjoy even greater value in the long run if they invest a little bit of their own money right now. They should feel like they're getting a great deal every time they spend money in your game. If you can keep this one principle in mind, all the rest of your monetization decisions should follow naturally.

Here's how it works in City Basher. All items are bought with either Points, Coins, or some combination of both. Some items are permanent, some get used up, and some last for a limited amount of time. Building cards and avatar decorations are permanent, as in a typical microtransaction-based game. But weapons and vehicles get used up - weapons are sold in the form of ammo, and vehicles can be used for a limited number of play sessions before they must be refueled. Only the starting weapon and vehicle last forever. This is like the rental approach to monetization. Lastly, membership cards to access special arenas and unlock special game enhancements are effective for a limited number of days before they expire, much like a subscription. Each of these items represents a different approach to microtransactions, in the hopes of appealing to as many different buying habits as possible and maximizing the revenue of the game.

Outside of the artillery game itself, there would be a sort of store interface where players could browse and shop for items. Building cards would be bought in random packs, from different editions, much like in an actual trading card game. Some editions could be bought only with Points, but the sets containing the more powerful cards must be bought with Coins. The idea is that players who really get into collecting cards are going to be the type to spend real money on the game. Avatar decorations are bought individually, mostly for Coins, though there might be some basic clothes and such that could be bought with Points instead.

Weapons are bought in bulk - that is, packs of ammunition - and for the most part can be bought with Points. For reasons of fairness, you want to be careful about charging real money for items that provide significant in-game advantages - like weapons - though it could be appropriate to charge Coins for some particularly strange or specialized types of weapons. Vehicles are similar, but since they have less of an effect on the fairness of the game, it is more appropriate to charge Coins for some of the vehicles, especially if their advantage is purely cosmetic or a matter of personal preference in the movement controls. Vehicles themselves do not get damaged or expire, but they do have a limited amount of fuel. Every time you enter a play session, you use up one unit of fuel in your chosen vehicle. The more powerful or expensive a vehicle, the more it costs to refuel it, though fuel should cost only Points since it is a recurring expense.

Arena access must be bought with Coins. Players buy membership cards, each of which provides access to several exclusive arenas for a certain amount of time. It might also be possible to include an arena editor that can be accessed in a similar way. This could be a nice place to incorporate player-created content, if you are so inclined. Other game enhancements can be bought individually with Coins, also for a limited amount of time. These may include advantages such as a larger maximum deck size, or extra weapon slots in each game. Most importantly, these enhancements would be the type of features that very dedicated players would appreciate and pay for, but that the average player would not find useful. This makes it acceptable to charge real money for such enhancements.

Permanent items - that is, building cards and avatar decorations as well as Coins and Points - can be traded freely between players. Temporary items like weapons and vehicles, however, may not. This is partly for simplicity, and partly because you want to use weapons and vehicles as a currency sink, a place where Coins and Points are removed from the game economy. And this role is undermined if players can just buy weapons from each other. In a real-world economy, this is not as important, but in a game where you can bring currency into circulation just by knocking over a few buildings, it's essential to drain that currency out of the system just as fast as it comes in, to avoid inflation. Since weapons and vehicles get used up over time, players must continually buy new ones, removing currency from circulation at a more or less constant rate. To keep the system running smoothly, you must continually balance item prices with the amount of Points that players can earn from each building type. Keep those Points flowing in and out at the same rate. No one said this would be easy!


To actually make City Basher, you'd need a good rigid-body physics engine, like motor2 or Glaze, or even Box2D. This could also be a great project for use with the PushButton Engine, since it has built-in Box2D support and an optional networking component for making multiplayer games.

However, making any multiplayer game on this scale is always going to be a massive undertaking. Make sure that you know what you are doing before you start. If you've never made a physics-based game before, start by making a single-player prototype of the basic building-destroying gameplay. Then, if you're new to network programming, make a simple match-based multiplayer version of the game, without the special items or persistent avatars.

If you can do that, and make it fun, then you can think about taking the next step and making it massive. When you do succeed in making a massively multiplayer game, don't add in all the special items all at once. Start with the basic free game, and add items gradually, careful not to upset the balance of the game. Incremental development is the way to go.

Good luck.


Required reading for anyone who wants to make a game like this:

Since Emanuele Feronato never showed up to receive his idea, City Basher is open to anyone to use for free! Even you. ;)

Let me know if you decide to try making it. I'd be glad to help however I can. Post a comment!

Want an idea? Make a request on The Game Idea Giveaway Thread!