At the start of your project, you usually decide what genre your game will belong to. Unless you come up with something completely new and previously unseen, chances
are high that your game idea fits into one of the broad genres currently popular. Most genres have established game mechanic standards (e.g., control schemes, specific goals, etc.). Deviating from these standards can make a game a great hit, as gamers always long for something new. It can also be a great risk, though, so consider carefully if your new platformer/first-person shooter/real-time strategy game actually has an audience.
Let's check out some examples for the more popular genres on the Android Market.
Probably the biggest segment of games on the Android Market consists of so-called causal games. So what exactly is a causal game? That question has no concrete answer, but causal games share a few common traits. Usually, they feature great accessibility, so even nongamers can pick them up easily, increasing the pool of potential players immensely. A game session is meant to take just a couple of minutes at most. However, the addictive nature of a causal game's simplicity often gets players hooked for hours. The actual game mechanics range from extremely simplistic puzzle games to one-button platformers to something as simple as tossing a paper ball into a basket. The possibilities are endless due to the causal genre having such a blurry definition.
Abduction and Abduction 2 (Figure 3-1), by the one-man shop Psym Mobile, is the perfect causal game. It belongs to the subgenre of jump-'em-up games (at least that's what I call them). The goal of the game is it to direct the always-jumping cow from platform to platform and reach the top of the level. On the way up you'll battle breaking platforms, spikes, and flying enemies. You can pick up power-ups that help you reach the top and so on. You control the cow by tilting the phone, thereby influencing the direction it is jumping/falling. Easy-to-understand controls, a clear goal, and cute graphics made this game one of the first hits on the Android Market.
Antigen (Figure 3-2), by Battery Powered Games, is a completely different animal. You play an antibody that fights against different kinds of viruses. The game is actually a hybrid action puzzler. You control the antibody with the onscreen D-pad and rotation buttons at the top right. Your antibody has a set of connectors at each side that allow you to connect to viruses and thereby destroy them—a simple but highly addictive concept. While Abduction only features a single input mechanism via the accelerometer, the controls of Antigen are a little bit more involved. As some devices do not support multitouch, the developers came up with a couple of input schemes for all possible devices, Zeemote controls being one of them. To reach the largest possible audience, special care was taken to make the game work even on low-end devices with 320x240 pixel screens.
Listing all the possible subgenres of the causal game category would probably fill up most of this book. Many more innovative game concepts can be found in this genre, and it is worth checking out the respective category in the market to get some inspiration.
Puzzle games need no introduction. We all know great games like Tetris and Bejeweled. They are a big part of the Android gaming market and highly popular with all segments of the demographic. In contrast to PC-based puzzle games, many puzzle games on Android deviate from the classic match-3 formula and use more elaborate, physics-based puzzles.
Super Tumble (Figure 3-3) is a superb example of a physics puzzler. The goal of the game is it to remove blocks by touching them, and get the star sitting on top of the blocks safely to the bottom platform. While this may sound fairly simple, it can get rather involved in later levels. The game is powered by Box2D, a 2D physics engine.
U Connect (Figure 3-4), by BitLogik, is a minimalistic but entertaining little brain-teaser. The goal is it to connect all the dots in the graph with a single line. Computer science students will probably recognize a familiar problem here.
CLEAR. MENÜ HINT I CLEAR. MEMO HINT
CLEAR. MENÜ HINT I CLEAR. MEMO HINT
MORE 0013 I MORE 0111
Figure 3-4. U Connect, by BitLogik
Of course, you can also find all kinds of Tetris clones, match-3 games, and other standard formulas on the market. The preceding games demonstrate that a puzzle game can be more than yet another clone of a 20-year-old concept.
Action and arcade games usually unleash the full potential of the Android platform. Many of them feature stunning 3D visuals, demonstrating what is possible on the current generation of hardware. The genre has many subgenres, including racing games, shoot-'em-ups, first- and third-person shooters, and platformers. This segment of the Android Market is still a little underdeveloped, as big companies that have the resources to produce such titles are hesitant to jump on the Android wagon. Some indie developers have taken it upon themselves to fill that niche, though.
Replica Island (Figure 3-5) is probably the most successful platformer on Android to date. It was developed by Google engineer and game development advocate Chris Pruett in an attempt to show that one can write high-performance games in pure Java on Android. The game tries to accommodate all potential device configurations by offering a huge variety of input schemes. Special care was taken that the game performs well even on low-end devices. The game itself involves a robot that is instructed to retrieve a mysterious artifact. The game mechanics resemble the old SNES 16-bit platformers. In the standard configuration, the robot is moved via an accelerometer and two buttons, one for enabling its thruster to jump over obstacles, and the other to stomp enemies from above. The game is also open source, which is another plus.
Exzeus (Figure 3-6), by HyperDevBox, is a classic rail shooter in the spirit of Starfox on the SNES, with high-fidelity 3D graphics. The game features it all: different weapons, power-ups, big boss fights, and a ton of things to shoot. As with many other 3D titles, the game is meant to be played on high-end devices only. The main character is controlled via tilt and onscreen buttons—a rather intuitive control scheme for this type of game.
Deadly Chambers (Figure 3-7), by Battery Powered Games, is a third-person shooter in the style of such classics as Doom and Quake. The main character, Dr. Chambers, tries to get out of the dungeons of the evil wizard in the tower. Battery Powered Games also sticks to the standard of not having an elaborate backstory for their shooter. But who needs that if you can just mindlessly kill everything that gets in your way with a fine set of exquisite weapons? The main character is controlled via an onscreen analog stick. Additional buttons allow the player to switch into a first-person perspective for more fine-grained aiming, switching weapons, and so on. In contrast to Exzeus, the developer took great care to make the game run even on low-end devices. The game also offers a variety of input schemes, so you can even play the game on single-touch screens. Technically, the game is a major feat, especially considering that it was programmed by a single person over a period of roughly six months.
Figure 3-7. Deadly Chambers, by Battery Powered Games
Radiant (Figure 3-8), by Hexage, represents a brilliant evolutionary step from the old Space Invaders concept. Instead of offering a static playfield, the game presents side-scrolling levels, and has quite a bit of variety in level and enemy design. You control the ship by tilting the phone, and you can upgrade the ship's weapon systems by buying new weapons with points you've earned by shooting enemies. The semi-pixelated style of the graphics give this game a unique look and feel while bringing back memories of the old days.
Figure 3-8. Radiant, by Hexage
The action and arcade genre is still a bit underrepresented on the market. Players are longing for good action titles, so maybe that is your niche!
Given their immense success on the Android platform, I felt the need to discuss tower-defense games as their own genre. Tower-defense games became popular as a variant of PC real-time strategy games developed by the modding community. The concept was soon translated to standalone games. Tower-defense games currently represent the best-selling genre on Android.
In a typical tower-defense game, some mostly evil force is sending out critters in so-called waves to attack your castle/base/crystals/you name it. Your task is to defend that special place on the game map by placing defense turrets that shoot the incoming enemies. For each enemy you kill, you usually get some amount of money or points that you can invest in new turrets or upgrades.
The concept is extremely simple, but getting the balance of such a game right is quite difficult.
Robo Defense (Figure 3-9), by Lupis Labs Software, is the mother of all tower-defense games on Android. It has occupied the number-one paid game spot in the market for most of Android's lifetime. The game follows the standard tower-defense formula without any bells and whistles attached. It's a straightforward and dangerously addictive tower-defense implementation, with different pannable maps, achievements, and high scores. The presentation is sufficient to get the concept across, but not stellar, which offers more proof that a selling game doesn't necessarily need to feature cream-of-the-crop graphics and audio.
Some games just can't be put into a category. They exploit the new capabilities and features of Android devices, such as the camera or the GPS, to create new sorts of experiences. This innovative crop of new games is social and location-aware, and even introduces some elements from the field of augmented reality.
SpecTrek (Figure 3-10) is one of the winners of the second Android Developer Challenge. The goal of the game is to roam around with GPS enabled to find ghosts and catch them with your camera. The ghosts are simply laid over a camera view, and it is the player's task to keep them in focus and press the Catch button to score points.
So, now that you know what's already available on Android, I suggest firing up the Market application and checking out some of the games presented previously. Pay attention to their structure (e.g., what screens lead to what other screens, what buttons do what, how game elements interact with each other, and so on). Getting a feeling for these things can actually be achieved by playing games with an analytic mindset. Push away the entertainment factor for a moment and concentrate on deconstructing the game. Once you're done, come back and read on. We are going to design a very simple game on paper.
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